Medial stabilized orthopaedic knee prosthesis

ABSTRACT

An orthopaedic knee prosthesis includes a tibial insert and a femoral component configured to articulate on the tibial insert. The tibial insert includes a lateral articular surface and medial articular surface that is asymmetrically shaped relative to the lateral articular surface. The medial articular surface is shaped to reduce anterior translation of a medial condyle of the femoral component, while the lateral articular surface is shaped to allow a lateral condyle of the femoral component to pivot, relative to the medial articular surface, along an arcuate articular path. Additionally, one or both condyles of the femoral component may include a femoral articular surface having a curved femoral surface section defined by a continuously decreasing radius of curvature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to U.S.Provisional Patent Application Ser. No. 63/050,744, entitled“ORTHOPAEDIC KNEE PROSTHESIS SYSTEM AND METHODS FOR USING SAME,” whichwas filed on Jul. 10, 2020 and is expressly incorporated by referenceinto the present application.

TECHNICAL FIELD

The present disclosure relates to orthopaedic knee prosthesis systemsand, more specifically, to orthopaedic knee prosthesis, instrumentation,and methods for total knee arthroplasty procedures.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased and/or damaged natural joint is replaced by a prosthetic joint.A typical knee prosthesis includes a tibial tray, a femoral component,and a polymer insert or bearing positioned between the tibial tray andthe femoral component. Depending on the severity of the damage to thepatient's joint, orthopaedic prostheses of varying mobility may be used.For example, the knee prosthesis may include a “fixed” tibial insert insome cases wherein it is desirable to limit the movement of the kneeprosthesis, such as when significant soft tissue damage or loss ispresent. Alternatively, the knee prosthesis may include a “mobile”tibial insert in cases wherein a greater degree of freedom of movementis desired. Additionally, the knee prosthesis may be a total kneeprosthesis designed to replace the femoral-tibial interface of bothcondyles of the patient's femur or a uni-compartmental (or uni-condylar)knee prosthesis designed to replace the femoral-tibial interface of asingle condyle of the patient's femur.

The type of orthopedic knee prosthesis used to replace a patient'snatural knee may also depend on whether the patient's posterior cruciateligament is retained or sacrificed (i.e., removed) during surgery. Forexample, if the patient's posterior cruciate ligament is damaged,diseased, and/or otherwise removed during surgery, aposterior-stabilized knee prosthesis may be used to provide additionalsupport and/or control at later degrees of flexion. Alternatively, ifthe posterior cruciate ligament is intact, a cruciate-retaining kneeprosthesis may be used.

Typical orthopaedic knee prostheses are generally designed to duplicatethe natural movement of the patient's joint. As the knee is flexed andextended, the femoral and tibial components articulate and undergocombinations of relative anterior-posterior motion and relativeinternal-external rotation. However, the patient's surrounding softtissue also impacts the kinematics and stability of the orthopaedic kneeprosthesis throughout the joint's range of motion. That is, forcesexerted on the orthopaedic components by the patient's soft tissue maycause unwanted or undesirable motion of the orthopaedic knee prosthesis.For example, the orthopaedic knee prosthesis may exhibit an amount ofunnatural (paradoxical) anterior translation as the femoral component ismoved through the range of flexion.

SUMMARY

According to one aspect, a tibial insert includes a lateral articularsurface and a medial articular surface. The lateral articular surface isconfigured to articulate with a lateral condyle of a femoral componentand includes an arcuate articular path extending in ananterior-posterior direction. The arcuate articular path is defined by aplurality of points on the lateral articular surface and, when thetibial insert is viewed in a cross-sectional medial-lateral plane ateach point, each point defines a distal-most point of the lateralarticular surface in the corresponding cross-sectional medial-lateralplane. The lateral articular surface has a cross-sectional concavecurvature orthogonal to the arcuate articular path, the cross-sectionalconcave curvature being uniform at each of the plurality of points. Themedial articular surface is configured to articulate with a medialcondyle of the femoral component. The medial articular surface isasymmetrically shaped relative to the lateral articular surface and hasa coronal concave curvature that is non-uniform in theanterior-posterior direction.

In an embodiment, the medial articular surface includes a medial dwellpoint that defines a distal-most point of the medial articular surface.The coronal concave curvature of the medial articular surface isnon-uniform anterior of the medial dwell point and uniform posterior ofthe medial dwell point.

In an embodiment, the arcuate articular path when viewed in across-sectional plane has a curvature that includes a semi-planarsection, an anterior curved section located anterior of the planarsection, and a plurality of posterior curved sections located posteriorof the planar section. The semi-planar section defines a lateral dwellregion that defines a distal-most area of the lateral articular surface.In an embodiment, each posterior curved section is defined by acorresponding radius of curvature, wherein the radii of curvature of theplurality of posterior curved sections decrease posteriorly.

In an embodiment, the plurality of posterior curved sections includes afirst posterior curved section adjacent to a posterior-most end of theplanar section and a second posterior curved section adjacent to thefirst posterior curved section, wherein a radius of curvature of thefirst posterior curved section is greater than a radius of curvature ofthe second posterior curved section. In an embodiment, the anteriorcurved section is defined by a corresponding radius of curvature that is(i) less than the radius of curvature of the first posterior curvedsection and (ii) greater than the radius of curvature of the secondposterior curved section. In an embodiment, the anterior curved sectionextends for an arc length in the range of 33.5 degrees to 34.4 degrees,the first posterior curved section extends for about 3.4 degrees, andthe second posterior curved section extends for an arc length in therange of 13.2 degrees to 13.7 degrees.

In an embodiment, the medial articular surface includes a sagittalconcave curvature, when viewed in a sagittal plane, that is defined by aplurality of curved sections and a medial dwell point that defines adistal-most point of the medial articular surface, wherein the medialdwell point is located on the sagittal concave curvature. In anembodiment, the plurality of curved sections includes a first curvedsection adjacent to the medial dwell point and extending posteriortherefrom and a second curved section adjacent the medial dwell pointand extending anterior therefrom, wherein a radius of curvature of thefirst curved section is greater than a radius of curvature of the secondcurved section. In an embodiment, the first curved section extends foran arc length of in the range of 15.9 degrees to 17.4 degrees and thesecond curved section extends for about 5.2 degrees.

In an embodiment, the plurality of curved sections includes a thirdcurved section adjacent to the second curved section and extendinganterior therefrom, a fourth curved section adjacent to the third curvedsection and extending anterior therefrom, and a fifth curved sectionadjacent the fourth curved section and extending anterior therefrom. Aradius of curvature of the third curved section is less that the radiusof curvature of the second curved section, less than a radius ofcurvature of the fourth curved section, and less than a radius of thefifth radius of curvature. In an embodiment, the third curved sectionextends for an arc length in the range of 14.8 degrees to 24.8 degrees,the fourth curved section extends for an arc length in the range of 10.7degrees to 20.7 degrees, and the fifth radius of curvature extends foran arc length in the range of 0.2 degrees to 6.3 degrees.

In an embodiment, the coronal concave curvature of the medial articularsurface is defined by a plurality of coronal curvatures including afirst coronal curvature that crosses the sagittal concave curvature ofthe medial articular surface at the medial dwell point, a second coronalcurvature located anteriorly to the first coronal curvature, a thirdcoronal curvature located anteriorly to the second coronal curvature,wherein each of the first, second, and third coronal curvatures aredifferent from each other. In an embodiment, the first coronal curvatureis defined by a coronal curved section that extends for an arc length inthe range of 18.6 degrees to 26.8 degrees medially from the medial dwellpoint and for about 25.0 degrees laterally from the medial dwell point.In an embodiment, the second coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the third curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the second coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from a lateral end of the planarsection. In an embodiment, a radius of curvature of the first coronalcurved section of the second coronal curvature is less than a radius ofcurvature of the second coronal curved section of the second coronalcurvature. In an embodiment, the first coronal curved of the secondcoronal curvature section extends for an arc length in the range of 14.7degrees to 15.7 degrees and the second coronal curved section of thesecond coronal curvature extends for an arc length in the range of 20.1degrees to 28.5 degrees.

In an embodiment, the third coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the fourth curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface. The third coronal curvature is defined by a planar sectionhaving a medial end and a lateral end, a first coronal curved sectionextending from the medial end of the planar section, and a secondcoronal curved section extending from the lateral end of the planarsection. In an embodiment, the planar section of the third coronalcurvature is angled about 6 degrees relative to a bottom surface of thetibial insert. In an embodiment, the first coronal curved section of thethird coronal curvature extends for an arc length in the range of 0.3degrees to 0.9 degrees and the second coronal curved section of thethird coronal curvature extends for an arc length in the range of 16.4degrees to 24.7 degrees.

In an embodiment, the tibial insert further includes an anteriorsidewall and a posterior sidewall opposite the anterior side, wherein adistance between the anterior sidewall and the posterior sidewalldefines an anterior-posterior length of the tibial insert. The medialarticular surface includes a medial dwell point that defines adistal-most point of the medial articular surface, wherein the medialdwell point is located about 63.3% of the anterior-posterior length fromthe anterior end.

In an embodiment, the medial articular surface includes a medial dwellpoint that defines a distal-most point of the medial articular surface,and the arcuate articular path of the lateral articular surface, whenviewed in a transverse plane, is defined by a radius of curvature havingan origin on the medial dwell point.

In an embodiment, the tibial insert further includes a first portion ofa locking mechanism located on a bottom surface of the tibial insert.The first portion of the locking mechanism is configured to mate with asecond portion of the locking mechanism located on a tibial base tosecure the tibial insert to the tibial base.

According to another aspect, a tibial insert includes a lateralarticular surface and a medial articular surface. The lateral articularsurface is configured to articulate with a lateral condyle of a femoralcomponent and includes an arcuate articular path extending in ananterior-posterior direction. The arcuate articular path when viewed ina cross-section plane has a curvature that includes a semi-planarsection, wherein the semi-planar section defines a distal-most area ofthe lateral articular surface. The medial articular surface isconfigured to articulate with a medial condyle of the femoral component.The medial articular surface is asymmetrically shaped relative to thelateral articular surface and includes a medial dwell point that definesa distal-most point of the medial condyle surface. The medial dwellpoint is located on the medial condyle surface (i) between a firstimaginary medial-lateral bisecting line of the tibial insert thatincludes an anterior-most end of the planar section of the sagittalcurvature of the lateral articular surface and a second imaginarymedial-lateral bisecting line of the tibial insert that includes aposterior-most end of the planar section of the sagittal curvature ofthe lateral articular surface and (ii) posterior to ananterior-posterior midpoint of the planar section of the sagittalcurvature of the lateral articular surface.

In an embodiment, the tibial insert further includes an anteriorsidewall and a posterior sidewall opposite the anterior side, wherein adistance between the anterior sidewall and the posterior sidewalldefines an anterior-posterior length of the tibial insert. The medialdwell point is located about 63.3% of the anterior-posterior length fromthe anterior end.

In an embodiment, the medial articular surface has a coronal concavecurvature that is non-uniform anterior of the medial dwell point anduniform posterior of the medial dwell point.

In an embodiment, the curvature of the arcuate articular path, whenviewed in the cross-section plane, further includes an anterior curvedsection located anterior of the semi-planar section and a plurality ofposterior curved sections located posterior of the semi-planar section.In an embodiment, each posterior curved section is defined by acorresponding radius of curvature, and the radii of curvature of theplurality of posterior curved sections decrease posteriorly. In anembodiment, the plurality of posterior curved sections includes a firstposterior curved section adjacent to the posterior-most end of theplanar section and a second posterior curved section adjacent to thefirst posterior curved section, wherein a radius of curvature of thefirst posterior curved section is greater than a radius of curvature ofthe second posterior curved section. In an embodiment, the anteriorcurved section is defined by a corresponding radius of curvature that is(i) less than the radius of curvature of the first posterior curvedsection and (ii) greater than radius of curvature of the secondposterior curved section. In an embodiment, the anterior curved sectionextends for an arc length in the range of 33.5 degrees to 34.4 degrees,the first posterior curved section extends for about 3.4 degrees, andthe second posterior curved section extends for an arc length in therange of 13.2 degrees to 13.7 degrees.

In an embodiment, the medial articular surface includes a sagittalconcave curvature, when viewed in a sagittal plane, that is defined by aplurality of curved sections, wherein the medial dwell point is locatedon the sagittal concave curvature. In an embodiment, the plurality ofcurved sections includes a first curved section adjacent to the medialdwell point and extending posterior therefrom and a second curvedsection adjacent the medial dwell point and extending anteriortherefrom, wherein a radius of curvature of the first curved section isgreater than a radius of curvature of the second curved section. In anembodiment, the first curved section extends for an arc length of in therange of 15.9 degrees to 17.4 degrees and the second curved sectionextends for about 5.2 degrees.

In an embodiment, the plurality of curved sections includes a thirdcurved section adjacent to the second curved section and extendinganterior therefrom, a fourth curved section adjacent to the third curvedsection and extending anterior therefrom, and a fifth curved sectionadjacent the fourth curved section and extending anterior therefrom,wherein a radius of curvature of the third curved section is less thatthe radius of curvature of the second curved section, less than a radiusof curvature of the fourth curved section, and less than a radius of thefifth radius of curvature. In an embodiment, the third curved sectionextends for an arc length in the range of 14.8 degrees to 24.8 degrees,the fourth curved section extends for an arc length in the range of 10.7degrees to 20.7 degrees, and the fifth radius of curvature extends foran arc length in the range of 0.2 degrees to 6.3 degrees.

In an embodiment, the medial articular surface has a coronal curvaturedefined by a plurality of coronal curvatures including a first coronalcurvature that crosses the sagittal concave curvature of the medialarticular surface at the medial dwell point, a second coronal curvaturelocated anteriorly to the first coronal curvature, a third coronalcurvature located anteriorly to the second coronal curvature, whereineach of the first, second, and third coronal curvatures are differentfrom each other. In an embodiment, the first coronal curvature isdefined by a coronal curved section that extends for an arc length inthe range of 18.6 degrees to 26.8 degrees medially from the medial dwellpoint and for about 25.0 degrees laterally from the medial dwell point.

In an embodiment, the second coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the third curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the second coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from a lateral end of the planarsection. In an embodiment, a radius of curvature of the first coronalcurved section of the second coronal curvature is less than a radius ofcurvature of the second coronal curved section of the second coronalcurvature. In an embodiment, the first coronal curved of the secondcoronal curvature section extends for an arc length in the range of 14.7degrees to 15.7 degrees and the second coronal curved section of thesecond coronal curvature extends for an arc length in the range of 20.1degrees to 28.5 degrees.

In an embodiment, the third coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the fourth curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the third coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from the lateral end of theplanar section. In an embodiment, the planar section of the thirdcoronal curvature is angled about 6 degrees relative to a bottom surfaceof the tibial insert. In an embodiment, the first coronal curved sectionof the third coronal curvature extends for an arc length in the range of0.3 degrees to 0.9 degrees and the second coronal curved section of thethird coronal curvature extends for an arc length in the range of 16.4degrees to 24.7 degrees.

In an embodiment, the arcuate articular path, when viewed in atransverse plane, is defined by a radius of curvature having an originon the medial dwell point.

In an embodiment, the tibial insert further includes a first portion ofa locking mechanism located on a bottom surface of the tibial insert.The first portion of the locking mechanism is configured to mate with asecond portion of the locking mechanism located on a tibial base tosecure the tibial insert to the tibial base.

According to another aspect, a tibial insert includes a lateralarticular surface configured to articulate with a lateral condyle of afemoral component and a medial articular surface configured toarticulate with a medial condyle of the femoral component. The lateralarticular surface includes an arcuate articular path extending in ananterior-posterior direction, a lateral dwell point that defines adistal-most point on the lateral articular surface located on thearcuate articular path, and an anterior lateral lip, wherein aninferior-superior distance between the lateral dwell point and asuperior-most point of the anterior lateral lip defines a lip height ofthe anterior lateral lip. The medial articular surface is asymmetricallyshaped relative to the lateral articular surface and includes a medialdwell point that defines a distal-most point on the medial articularsurface and an anterior medial lip, wherein an inferior-superiordistance between the medial dwell point and a superior-most point on themedial lateral lip defines a lip height of the anterior medial lip. Thelip height of the anterior medial lip is greater than the lip height ofthe anterior lateral lip, and a ratio of the lip height of the anteriormedial lip to an anterior-posterior distance between an anteriorsidewall of the medial articular surface and a posterior sidewall of themedial articular surface is in the range of 18.9% to 20.9%.

In an embodiment, the medial articular surface has a coronal concavecurvature that is non-uniform anterior of the medial dwell point anduniform posterior of the medial dwell point.

In an embodiment, the arcuate articular path, when viewed in thecross-section plane, has curvature that includes a semi-planar section,an anterior curved section located anterior of the planar section, and aplurality of posterior curved sections located posterior of the planarsection. The lateral dwell point is located on the semi-planar section.

In an embodiment, each posterior curved section is defined by acorresponding radius of curvature, wherein the radii of curvature of theplurality of posterior curved sections decrease posteriorly.

In an embodiment, the plurality of posterior curved sections includes afirst posterior curved section adjacent to a posterior-most end of theplanar section and a second posterior curved section adjacent to thefirst posterior curved section, wherein a radius of curvature of thefirst posterior curved section is greater than a radius of curvature ofthe second posterior curved section. In an embodiment, an anteriorcurved section is defined by a corresponding radius of curvature that is(i) less than the radius of curvature of the first posterior curvedsection and (ii) greater than radius of curvature of the secondposterior curved section. In an embodiment, the anterior curved sectionextends for an arc length in the range of 33.5 degrees to 34.4 degrees,the first posterior curved section extends for about 3.4 degrees, andthe second posterior curved section extends for an arc length in therange of 13.2 degrees to 13.7 degrees.

In an embodiment, the medial articular surface includes a sagittalconcave curvature, when viewed in a sagittal plane, that is defined by aplurality of curved sections, wherein the medial dwell point is locatedon the sagittal concave curvature. In an embodiment, the plurality ofcurved sections includes a first curved section adjacent to the medialdwell point and extending posterior therefrom and a second curvedsection adjacent the medial dwell point and extending anteriortherefrom, wherein a radius of curvature of the first curved section isgreater than a radius of curvature of the second curved section. In anembodiment, the first curved section extends for an arc length of in therange of 15.9 degrees to 17.4 degrees and the second curved sectionextends for about 5.2 degrees.

In an embodiment, the plurality of curved sections includes a thirdcurved section adjacent to the second curved section and extendinganterior therefrom, a fourth curved section adjacent to the third curvedsection and extending anterior therefrom, and a fifth curved sectionadjacent the fourth curved section and extending anterior therefrom,wherein a radius of curvature of the third curved section is less thatthe radius of curvature of the second curved section, less than a radiusof curvature of the fourth curved section, and less than a radius of thefifth radius of curvature. In an embodiment, the third curved sectionextends for an arc length in the range of 14.8 degrees to 24.8 degrees,the fourth curved section extends for an arc length in the range of 10.7degrees to 20.7 degrees, and the fifth radius of curvature extends foran arc length in the range of 0.2 degrees to 6.3 degrees.

In an embodiment, the medial articular surface has a coronal curvaturedefined by a plurality of coronal curvatures including a first coronalcurvature that crosses the sagittal concave curvature of the medialarticular surface at the medial dwell point, a second coronal curvaturelocated anteriorly to the first coronal curvature, a third coronalcurvature located anteriorly to the second coronal curvature, whereineach of the first, second, and third coronal curvatures are differentfrom each other. In an embodiment, the first coronal curvature isdefined by a coronal curved section that extends for an arc length inthe range of 18.6 degrees to 26.8 degrees medially from the medial dwellpoint and for about 25.0 degrees laterally from the medial dwell point.

In an embodiment, the second coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the third curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the second coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from a lateral end of the planarsection. In an embodiment, a radius of curvature of the first coronalcurved section of the second coronal curvature is less than a radius ofcurvature of the second coronal curved section of the second coronalcurvature. In an embodiment, the first coronal curved of the secondcoronal curvature section extends for an arc length in the range of 14.7degrees to 15.7 degrees and the second coronal curved section of thesecond coronal curvature extends for an arc length in the range of 20.1degrees to 28.5 degrees.

In an embodiment, the third coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the fourth curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the third coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from the lateral end of theplanar section. In an embodiment, the planar section of the thirdcoronal curvature is angled about 6 degrees relative to a bottom surfaceof the tibial insert. In an embodiment, the first coronal curved sectionof the third coronal curvature extends for an arc length in the range of0.3 degrees to 0.9 degrees and the second coronal curved section of thethird coronal curvature extends for an arc length in the range of 16.4degrees to 24.7 degrees.

In an embodiment, the tibial insert further includes an anterior sideand a posterior side opposite the anterior side. A distance between theanterior side and the posterior side defines an anterior-posteriorlength of the tibial insert. The medial dwell point is located about63.3% of the anterior-posterior length from the anterior end. In anembodiment, the arcuate articular path of the lateral articular surface,when viewed in a transverse plane, is defined by a radius of curvaturehaving an origin on the medial dwell point.

In an embodiment, the tibial insert further includes a first portion ofa locking mechanism located on a bottom surface of the tibial insert.The first portion of the locking mechanism is configured to mate with asecond portion of the locking mechanism located on a tibial base tosecure the tibial insert to the tibial base.

According to yet another aspect, an orthopaedic knee prosthesis includesa femoral component having a lateral condyle and a medial condyle and atibial insert having a lateral articular surface configured toarticulate with the lateral condyle of the femoral component and amedial articular surface configured to articulate with the medialcondyle of the femoral component. The medial condyle includes a femoralarticular surface defined by a plurality of curved femoral surfacesections that includes a first curved femoral surface section defined bya continually decreasing radius of curvature. The medial articularsurface is asymmetrically shaped relative to the lateral articularsurface and includes a medial dwell point that defines a distal-mostpoint on the medial articular surface. The medial condyle contacts themedial dwell point at a first contact point on the first curved femoralsurface section at a first degree of flexion and contacts the medialdwell point at a second contact point on the first curved femoralsurface section at a second degree of flexion, wherein the secondcontact point is posterior of the first contact point and wherein thesecond degree of flexion is greater than the first degree of flexion.The medial articular surface includes a sagittal concave curvature thathas a first sagittal conformity with the medial condyle at a locationanterior to dwell point at the first degree of flexion and a secondsagittal conformity with the medial condyle at the location anterior tothe dwell point at the second degree of flexion, wherein the secondsagittal conformity is greater than the first sagittal conformity toreduce anterior translation of the medial condyle at the second degreeof flexion.

In an embodiment, the medial condyle of femoral component includes asagittal convex curvature, and a sagittal conformity between thesagittal concave curvature of the medial articular surface and sagittalconcave curvature of the medial condyle is greater at a first degree offlexion of the femoral condyle than at extension. In an embodiment, thefirst degree of flexion is about 30 degrees.

In an embodiment, the medial articular surface includes a coronalconcave curvature and a coronal conformity between the coronal concavecurvature and the medial condyle at the degree of flexion is greater atthe medial dwell point of the medial articular surface than at thelocation on the medial articular surface that is anterior of the medialdwell point. In an embodiment, the medial articular surface isnon-uniform anterior of the medial dwell point and uniform posterior ofthe medial dwell point.

In an embodiment, the medial condyle and the medial articular surfaceare more conforming with each other than the lateral condyle and thelateral articular surface.

In an embodiment, the medial articular surface includes a coronalconcave curvature and a coronal conformity between the coronal concavecurvature and the medial condyle is greater when the femoral componentis positioned at extension than when the femoral component is positionedat a later degree of flexion.

In an embodiment, the lateral articular surface includes an arcuatearticular path that when viewed in a cross-section plane has a curvaturethat includes a planar section, an anterior curved section locatedanterior of the semi-planar section, and a plurality of posterior curvedsections located posterior of the planar section. the semi-planarsection defines a distal-most area of the lateral articular surface. Inan embodiment, each posterior curved section is defined by acorresponding radius of curvature, and wherein the radii of curvature ofthe plurality of posterior curved sections decrease posteriorly.

In an embodiment, the sagittal concave curvature of the medial articularsurface, when viewed in a sagittal plane, includes a plurality of curvedsections and wherein the medial dwell point is located on the sagittalconcave curvature. The plurality of curved sections includes a firstcurved section adjacent to the medial dwell point and extendingposterior therefrom, a second curved section adjacent the medial dwellpoint and extending anterior therefrom, a third curved section adjacentto the second curved section and extending anterior therefrom, a fourthcurved section adjacent to the third curved section and extendinganterior therefrom, and a fifth curved section adjacent the fourthcurved section and extending anterior therefrom. A radius of curvatureof the first curved section is greater than a radius of curvature of thesecond curved section and wherein a radius of curvature of the thirdcurved section is less that the radius of curvature of the second curvedsection, less than a radius of curvature of the fourth curved section,and less than a radius of the fifth radius of curvature.

In an embodiment, the medial articular surface includes a coronalconcave curvature that is defined by a plurality of coronal curvaturesincluding a first coronal curvature that crosses the sagittal concavecurvature of the medial articular surface at the medial dwell point, asecond coronal curvature located anteriorly to the first coronalcurvature, a third coronal curvature located anteriorly to the secondcoronal curvature, wherein each of the first, second, and third coronalcurvatures are different from each other. In an embodiment, the secondcoronal curvature crosses the sagittal concave curvature of the medialarticular surface at an anterior-most point of the third curved sectionof the plurality of curved sections that define the sagittal concavecurvature of the medial articular surface, wherein the second coronalcurvature is defined by a planar section having a medial end and alateral end, a first coronal curved section extending from the medialend of the planar section, and a second coronal curved section extendingfrom a lateral end of the planar section, and wherein a radius ofcurvature of the first coronal curved section is less than a radius ofcurvature of the second coronal curved section. In an embodiment, thethird coronal curvature crosses the sagittal concave curvature of themedial articular surface at an anterior-most point of the fourth curvedsection of the plurality of curved sections that define the sagittalconcave curvature of the medial articular surface, wherein the thirdcoronal curvature is defined by a planar section having a medial end anda lateral end, a first coronal curved section extending from the medialend of the planar section, and a second coronal curved section extendingfrom the lateral end of the planar section.

In an embodiment, the tibial insert further includes a first portion ofa locking mechanism located on a bottom surface of the tibial insert.The first portion of the locking mechanism is configured to mate with asecond portion of the locking mechanism located on a tibial base tosecure the tibial insert to the tibial base.

In an embodiment, a distal-most point of the femoral articular surfacewhen the femoral component is in extension defines zero degrees offlexion, and the first curved femoral surface section extends from afirst degree of flexion of about 5 degrees to a second degree of flexionof about 65 degrees. In an embodiment, the first curved femoral surfacesection is defined by a plurality of rays extending from a common originto a corresponding point on the second curved femoral surface section.Each ray has a length defined by the following polynomial equation:r_(θ)=(a+(b*θ)+(c*θ²)+(d*θ³)), wherein r_(θ) is the length of the raydefining a point on the second curved femoral surface section at θdegrees of flexion, a is a coefficient value between 20 and 50, and b isa coefficient value in a range selected from the group consisting of:−0.30<b<0.00, 0.00<b<0.30, and b=0, wherein when b is in the range of−0.30<b<0.00, (i) c is a coefficient value between 0.00 and 0.012 and(ii) d is a coefficient value between −0.00015 and 0.00, wherein whenbis in the range of 0<b<0.30, (i) c is a coefficient value between−0.010 and 0.00 and (ii) d is a coefficient value between −0.00015 and0.00, and wherein when b is equal to 0, (i) c is a coefficient value ina range selected from the group consisting of: −0.0020<c<0.00 and0.00<c<0.0025 and (ii) d is a coefficient value between −0.00015 and0.00.

In an embodiment, the plurality of curved femoral surface sectionsincludes a second curved femoral surface section posteriorly adjacentthe first curved femoral section, wherein the second curved femoralsurface section is defined by a constant radius of curvature greaterthan a posterior-most radii of curvature of the first curved femoralsurface section. In an embodiment, the second curved femoral surfacesection extends from a first degree of flexion of about 65 degrees to asecond degree of flexion of about 90.

According to another aspect, an orthopaedic knee prosthesis includes afemoral component having a lateral condyle and a medial condyle and atibial insert having a lateral articular surface configured toarticulate with the lateral condyle of the femoral component and amedial articular surface configured to articulate with the medialcondyle of the femoral component. The medial condyle includes a femoralarticular surface defined by a plurality of curved femoral surfacesections that includes a first curved femoral surface section and asecond curved femoral surface section posteriorly adjacent the firstcurved femoral surface section, wherein the first curved femoral surfacesection is defined by a continually decreasing radius of curvature andthe second curved femoral surface section is defined by a constantradius of curvature greater than a posterior-most radii of curvature ofthe first curved femoral surface section. The medial articular surfaceis asymmetrically shaped relative to the lateral articular surface andincludes a medial dwell point that defines a distal-most point on themedial articular surface. The medial condyle (i) contacts the medialdwell point at a first contact point on the first curved femoral surfacesection at a first degree of flexion, the first contact point beingdefined by the posterior-most radii of curvature of the first curvedfemoral surface section and (ii) contacts the medial dwell point at asecond contact point on the second curved femoral surface section at asecond degree of flexion greater than the first degree of flexion, thesecond contact point being defined by the constant radius of curvatureof the second curved femoral surface section. An inferior-superiordistance between the medial dwell point and an origin of the constantradius of curvature of the second curved femoral surface section at thesecond degree of flexion is greater than an inferior-superior distancebetween the medial dwell point and an origin of the posterior-most radiiof curvature of the first curved femoral surface section at the firstdegree of flexion.

In an embodiment, the medial condyle of femoral component includes asagittal convex curvature and the medial articular surface includes asagittal concave curvature, wherein a sagittal conformity between thesagittal concave curvature of the medial articular surface and sagittalconcave curvature of the medial condyle is greater at a first degree offlexion of the femoral condyle than at extension. In an embodiment, thefirst degree of flexion is about 30 degrees.

In an embodiment, the medial articular surface includes a sagittalconcave curvature, wherein at the medial dwell point the sagittalconcave curvature has a first sagittal conformity with the medialcondyle at a first degree of flexion of the femoral component, whereinat a location on the medial articular surface that is anterior of themedial dwell point the sagittal concave curvature has a second sagittalconformity with the medial condyle at the first degree of flexion, andwherein the second sagittal conformity is greater than the firstsagittal conformity.

In an embodiment, the medial articular surface includes a coronalconcave curvature, wherein at the medial dwell point the coronal concavecurvature has a first coronal conformity with the medial condyle at thefirst degree of flexion, wherein at the location on the medial articularsurface that is anterior of the medial dwell point the coronal concavecurvature has a second coronal conformity with the medial condyle at thefirst degree of flexion, and wherein the second coronal conformity isgreater than the first coronal conformity. In an embodiment, the medialarticular surface is non-uniform anterior of the medial dwell point anduniform posterior of the medial dwell point.

In an embodiment, the medial condyle and the medial articular surfaceare more conforming with each other than the lateral condyle and thelateral articular surface.

In an embodiment, the medial articular surface includes a coronalconcave curvature, wherein a coronal conformity between the coronalconcave curvature and the medial condyle is greater when the femoralcomponent is positioned at extension than when the femoral component ispositioned at a later degree of flexion.

In an embodiment, the lateral articular surface includes an arcuatearticular path that when viewed in a cross-section plane has a curvaturethat includes a semi-planar section, an anterior curved section locatedanterior of the semi-planar section, and a plurality of posterior curvedsections located posterior of the planar section. The planar sectiondefines a distal-most area of the lateral articular surface. In anembodiment, each posterior curved section is defined by a correspondingradius of curvature, wherein the radii of curvature of the plurality ofposterior curved sections decrease posteriorly.

In an embodiment, the sagittal concave curvature of the medial articularsurface, when viewed in a sagittal plane, includes a plurality of curvedsections, wherein the medial dwell point is located on the sagittalconcave curvature. The plurality of curved sections includes a firstcurved section adjacent to the medial dwell point and extendingposterior therefrom, a second curved section adjacent the medial dwellpoint and extending anterior therefrom, a third curved section adjacentto the second curved section and extending anterior therefrom, a fourthcurved section adjacent to the third curved section and extendinganterior therefrom, and a fifth curved section adjacent the fourthcurved section and extending anterior therefrom. A radius of curvatureof the first curved section is greater than a radius of curvature of thesecond curved section and wherein a radius of curvature of the thirdcurved section is less that the radius of curvature of the second curvedsection, less than a radius of curvature of the fourth curved section,and less than a radius of the fifth radius of curvature

In an embodiment, the medial articular surface includes a coronalconcave curvature that is defined by a plurality of coronal curvaturesincluding a first coronal curvature that crosses the sagittal concavecurvature of the medial articular surface at the medial dwell point, asecond coronal curvature located anteriorly to the first coronalcurvature, a third coronal curvature located anteriorly to the secondcoronal curvature, wherein each of the first, second, and third coronalcurvatures are different from each other.

In an embodiment, the second coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the third curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the second coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from a lateral end of the planarsection, and wherein a radius of curvature of the first coronal curvedsection is less than a radius of curvature of the second coronal curvedsection.

In an embodiment, the third coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the fourth curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the third coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from the lateral end of theplanar section.

In an embodiment, the tibial insert further includes a first portion ofa locking mechanism located on a bottom surface of the tibial insert,wherein the first portion of the locking mechanism is configured to matewith a second portion of the locking mechanism located on a tibial baseto secure the tibial insert to the tibial base.

In an embodiment, a distal-most point of the femoral articular surfacewhen the femoral component is in extension defines zero degrees offlexion, and the first curved femoral surface section extends from afirst degree of flexion of about 5 degrees to a second degree of flexionof about 65 degrees. In an embodiment, the first curved femoral surfacesection is defined by a plurality of rays extending from a common originto a corresponding point on the second curved femoral surface section.Each ray has a length defined by the following polynomial equation:r_(θ)=(a+(b*θ)+(c*θ²)+(d*θ³)), wherein r_(θ) is the length of the raydefining a point on the second curved femoral surface section at θdegrees of flexion, a is a coefficient value between 20 and 50, and b isa coefficient value in a range selected from the group consisting of:−0.30<b<0.00, 0.00<b<0.30, and b=0, wherein when b is in the range of−0.30<b<0.00, (i) c is a coefficient value between 0.00 and 0.012 and(ii) d is a coefficient value between −0.00015 and 0.00, wherein whenbis in the range of 0<b<0.30, (i) c is a coefficient value between−0.010 and 0.00 and (ii) d is a coefficient value between −0.00015 and0.00, and wherein when b is equal to 0, (i) c is a coefficient value ina range selected from the group consisting of: −0.0020<c<0.00 and0.00<c<0.0025 and (ii) d is a coefficient value between −0.00015 and0.00.

In an embodiment, the plurality of curved femoral surface sectionsincludes a second curved femoral surface section posteriorly adjacentthe first curved femoral section, wherein the second curved femoralsurface section is defined by a constant radius of curvature greaterthan a posterior-most radii of curvature of the first curved femoralsurface section. In an embodiment, the second curved femoral surfacesection extends from a first degree of flexion of about 65 degrees to asecond degree of flexion of about 90.

According to another aspect, an orthopaedic knee prosthesis includes afemoral component having a lateral condyle and a medial condyle and atibial insert having a lateral articular surface configured toarticulate with the lateral condyle of the femoral component and amedial articular surface configured to articulate with the medialcondyle of the femoral component. The medial condyle includes a femoralarticular surface defined by a plurality of curved femoral surfacesections that includes a first curved femoral surface section defined bya continually decreasing radius of curvature. The lateral articularsurface includes an arcuate articular path extending in ananterior-posterior direction, wherein the arcuate articular path whenviewed in a cross-section plane has a curvature that includes a planarsection and wherein the planar section defines a distal-most area of thelateral articular surface. The medial articular surface isasymmetrically shaped relative to the lateral articular surface andincludes a medial dwell point that defines a distal-most point of themedial condyle surface, and wherein the medial dwell point is located onthe medial condyle surface (i) between a first imaginary medial-lateralbisecting line of the tibial insert that includes an anterior-most endof the planar section of the sagittal curvature of the lateral articularsurface and a second imaginary medial-lateral bisecting line of thetibial insert that includes a posterior-most end of the planar sectionof the sagittal curvature of the lateral articular surface and (ii)posterior to an anterior-posterior midpoint of the planar section of thesagittal curvature of the lateral articular surface.

In an embodiment, the medial condyle of femoral component includes asagittal convex curvature and the medial articular surface includes asagittal concave curvature, and wherein a sagittal conformity betweenthe sagittal concave curvature of the medial articular surface andsagittal concave curvature of the medial condyle is greater at a firstdegree of flexion of the femoral condyle than at extension. In anembodiment, the first degree of flexion is about 30 degrees.

In an embodiment, the medial articular surface includes a sagittalconcave curvature, wherein at the medial dwell point the sagittalconcave curvature has a first sagittal conformity with the medialcondyle at a first degree of flexion of the femoral component, whereinat a location on the medial articular surface that is anterior of themedial dwell point the sagittal concave curvature has a second sagittalconformity with the medial condyle at the first degree of flexion, andwherein the second sagittal conformity is greater than the firstsagittal conformity.

In an embodiment, the medial articular surface includes a coronalconcave curvature, wherein at the medial dwell point the coronal concavecurvature has a first coronal conformity with the medial condyle at thefirst degree of flexion, wherein at the location on the medial articularsurface that is anterior of the medial dwell point the coronal concavecurvature has a second coronal conformity with the medial condyle at thefirst degree of flexion, and wherein the second coronal conformity isgreater than the first coronal conformity. In an embodiment, the medialarticular surface is non-uniform anterior of the medial dwell point anduniform posterior of the medial dwell point.

In an embodiment, the medial articular surface includes a coronalconcave curvature and a coronal conformity between the coronal concavecurvature and the medial condyle is greater when the femoral componentis positioned at extension than when the femoral component is positionedat a later degree of flexion.

In an embodiment, the arcuate articular path of the lateral articularsurface, when viewed in a cross-section plane, has a curvature thatincludes a semi-planar section, an anterior curved section locatedanterior of the planar section, and a plurality of posterior curvedsections located posterior of the planar section. The semi-planarsection defines a distal-most area of the lateral articular surface. Inan embodiment, each posterior curved section is defined by acorresponding radius of curvature, and wherein the radii of curvature ofthe plurality of posterior curved sections decrease posteriorly.

In an embodiment, the sagittal concave curvature of the medial articularsurface, when viewed in a sagittal plane, includes a plurality of curvedsections and wherein the medial dwell point is located on the sagittalconcave curvature. The plurality of curved sections includes a firstcurved section adjacent to the medial dwell point and extendingposterior therefrom, a second curved section adjacent the medial dwellpoint and extending anterior therefrom, a third curved section adjacentto the second curved section and extending anterior therefrom, a fourthcurved section adjacent to the third curved section and extendinganterior therefrom, and a fifth curved section adjacent the fourthcurved section and extending anterior therefrom. A radius of curvatureof the first curved section is greater than a radius of curvature of thesecond curved section and wherein a radius of curvature of the thirdcurved section is less that the radius of curvature of the second curvedsection, less than a radius of curvature of the fourth curved section,and less than a radius of the fifth radius of curvature.

In an embodiment, the medial articular surface includes a coronalconcave curvature that is defined by a plurality of coronal curvaturesincluding a first coronal curvature that crosses the sagittal concavecurvature of the medial articular surface at the medial dwell point, asecond coronal curvature located anteriorly to the first coronalcurvature, a third coronal curvature located anteriorly to the secondcoronal curvature, wherein each of the first, second, and third coronalcurvatures are different from each other.

In an embodiment, the second coronal curvature crosses the sagittalconcave curvature of the medial articular surface at a posterior-mostpoint of the third curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the second coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from a lateral end of the planarsection, and wherein a radius of curvature of the first coronal curvedsection is less than a radius of curvature of the second coronal curvedsection.

In an embodiment, the third coronal curvature crosses the sagittalconcave curvature of the medial articular surface at an anterior-mostpoint of the fourth curved section of the plurality of curved sectionsthat define the sagittal concave curvature of the medial articularsurface, wherein the third coronal curvature is defined by a planarsection having a medial end and a lateral end, a first coronal curvedsection extending from the medial end of the planar section, and asecond coronal curved section extending from the lateral end of theplanar section.

In an embodiment, the tibial insert further includes a first portion ofa locking mechanism located on a bottom surface of the tibial insert,wherein the first portion of the locking mechanism is configured to matewith a second portion of the locking mechanism located on a tibial baseto secure the tibial insert to the tibial base.

In an embodiment, a distal-most point of the femoral articular surfacewhen the femoral component is in extension defines zero degrees offlexion. The first curved femoral surface section extends from a firstdegree of flexion of about 5 degrees to a second degree of flexion ofabout 65 degrees. In an embodiment, the first curved femoral surfacesection is defined by a plurality of rays extending from a common originto a corresponding point on the second curved femoral surface section.Each ray has a length defined by the following polynomial equation:r_(θ)=(a+(b*θ)+(c*θ²)+(d*θ³)), wherein r_(θ) is the length of the raydefining a point on the second curved femoral surface section at θdegrees of flexion, a is a coefficient value between 20 and 50, and b isa coefficient value in a range selected from the group consisting of:−0.30<b<0.00, 0.00<b<0.30, and b=0, wherein when b is in the range of−0.30<b<0.00, (i) c is a coefficient value between 0.00 and 0.012 and(ii) d is a coefficient value between −0.00015 and 0.00, wherein whenbis in the range of 0<b<0.30, (i) c is a coefficient value between−0.010 and 0.00 and (ii) d is a coefficient value between −0.00015 and0.00, and wherein when b is equal to 0, (i) c is a coefficient value ina range selected from the group consisting of: −0.0020<c<0.00 and0.00<c<0.0025 and (ii) d is a coefficient value between −0.00015 and0.00.

In an embodiment, the plurality of curved femoral surface sectionsincludes a second curved femoral surface section posteriorly adjacentthe first curved femoral section, wherein the second curved femoralsurface section is defined by a constant radius of curvature greaterthan a posterior-most radii of curvature of the first curved femoralsurface section. In an embodiment, the second curved femoral surfacesection extends from a first degree of flexion of about 65 degrees to asecond degree of flexion of about 90.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is an exploded perspective view of an embodiment of anorthopaedic knee prosthesis;

FIG. 2 is lateral perspective view of the orthopaedic knee prosthesis ofFIG. 1 in an assembled configuration;

FIG. 3 is an anterior elevation view of the orthopaedic knee prosthesisof FIG. 1 ;

FIG. 4 is a side elevation view of an embodiment of a femoral componentof the orthopaedic knee prosthesis of FIG. 1 ;

FIG. 5 is a table of an embodiment of ending degrees of flexion forradii of curvature for a family of femoral component sizes of thefemoral component of FIG. 4 ;

FIG. 6 is a table of an embodiment of radii of curvature length valuesand corresponding ratios for a family of femoral component sizes of thefemoral component of FIG. 4 ;

FIG. 7 is a table of an embodiment of coefficient values of a polynomialequation that may define a curved surface section of one or more condylesurfaces of the femoral component of FIG. 4 ;

FIG. 8 is a superior plan view of a tibial insert of the orthopaedicknee prosthesis of FIG. 1 illustrating a lateral arcuate articular path;

FIG. 9 is another superior plan view of the tibial insert of FIG. 8illustrating a lateral dwell region;

FIG. 10 is an inferior perspective view of the tibial insert of FIG. 8 ;

FIG. 11 is an inferior plan view of the tibial insert of FIG. 8 ;

FIG. 12 is an anterior elevation view of the tibial insert of FIG. 8 ;

FIG. 13 is a posterior elevation view of the tibial insert of FIG. 8 ;

FIG. 14 is a lateral elevation view of the tibial insert of FIG. 8 ;

FIG. 15 is a medial elevation view of the tibial insert of FIG. 8 ;

FIG. 16 is a cross-sectional view of a lateral articulation surface ofthe tibial insert of FIG. 8 in a illustrating a lateral dwell region;

FIG. 17 is a cross-sectional view of a medial articulation surface ofthe tibial insert of FIG. 8 in a sagittal plane illustrating a medialdwell point;

FIG. 18 is a perspective view of the tibial insert of FIG. 8illustrating sagittal and coronal curvatures of the articular surfacesof the tibial insert;

FIG. 19 is a superior plan view of the tibial insert of FIG. 8 showingseveral cross-sectional cut lines;

FIG. 20 is a cross-sectional view of a lateral articulation surface ofan embodiment of the tibial insert of FIG. 8 in a complex plane alongthe line 20-20 in FIG. 19 ;

FIG. 21 is a cross-sectional view of a lateral articulation surface ofanother embodiment of the tibial insert of FIG. 8 in a complex planealong the line 20-20 in FIG. 19 ;

FIG. 22 is a cross-sectional view of a medial articulation surface of anembodiment of the tibial insert of FIG. 8 in a sagittal plane along theline 22-22 in FIG. 19 ;

FIG. 23 is a cross-sectional view of the lateral articulation surface ofan embodiment of the tibial insert of FIG. 8 in a coronal plane alongthe line 23-23 in FIG. 19 ;

FIG. 24 is a cross-sectional view of the medial articulation surface ofan embodiment of the tibial insert of FIG. 8 in a coronal plane alongthe line 24-24 in FIG. 19 ;

FIG. 25 is a cross-sectional view of the medial articulation surface ofanother embodiment of the tibial insert of FIG. 8 in a coronal planealong the line 24-24 in FIG. 19 ;

FIG. 26 is another cross-sectional view of the medial articulationsurface of an embodiment of the tibial insert of FIG. 8 in a coronalplane along the line 26-26 in FIG. 19 ;

FIG. 27 is another cross-sectional view of the medial articulationsurface of an embodiment of the tibial insert of FIG. 8 in a coronalplane along the line 27-27 in FIG. 19 ;

FIG. 28 is a medial elevation view of the orthopaedic knee prosthesis ofFIG. 1 at about 0 degrees of flexion;

FIG. 29 is a medial elevation view of the orthopaedic knee prosthesis ofFIG. 1 at about 35 degrees of flexion;

FIG. 30 is a medial elevation view of the orthopaedic knee prosthesis ofFIG. 1 at about 90 degrees of flexion;

FIG. 31 is a medial elevation view of the orthopaedic knee prosthesis ofFIG. 1 at about 110 degrees of flexion;

FIG. 32 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 28 in a coronal plan along the line 32-32 in FIG. 28 ;

FIG. 33 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 28 in a transverse plane along the line 33-33 in FIG. 28 ;

FIG. 34 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 28 in a sagittal plan along a medial dwell point of a medialarticular surface of the tibial insert of the orthopaedic kneeprosthesis of FIG. 28 ;

FIG. 35 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 29 in a coronal plan along the line 35-35 in FIG. 29 ;

FIG. 36 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 29 in a transverse plane along the line 36-36 in FIG. 29 ;

FIG. 37 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 29 in a sagittal plan along a medial dwell point of a medialarticular surface of the tibial insert of the orthopaedic kneeprosthesis of FIG. 29 ;

FIG. 38 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 30 in a coronal plan along the line 38-38 in FIG. 30 ;

FIG. 39 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 30 in a transverse plane along the line 39-39 in FIG. 30 ;

FIG. 40 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 30 in a sagittal plan along a medial dwell point of a medialarticular surface of the tibial insert of the orthopaedic kneeprosthesis of FIG. 30 ;

FIG. 41 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 31 in a coronal plan along the line 41-41 in FIG. 31 ;

FIG. 42 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 31 in a transverse plane along the line 42-42 in FIG. 31 ;

FIG. 43 is a cross-sectional view of the orthopaedic knee prosthesis ofFIG. 31 in a sagittal plan along a medial dwell point of a medialarticular surface of the tibial insert of the orthopaedic kneeprosthesis of FIG. 31 ;

FIG. 44 is a lateral elevation view of the orthopaedic knee prosthesisof FIG. 1 flexed to a degree of flexion and showing a point of contactdefined by a radius of curvature; and

FIG. 45 is a lateral elevation view of the orthopaedic knee prosthesisof FIG. 1 flexed to a degree of flexion slightly greater than FIG. 44and showing another point of contact defined by another radius ofcurvature.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific illustrative embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthe specification in reference to the orthopaedic implants and/orsurgical instruments described herein as well as in reference to thepatient's natural anatomy. Such terms have well-understood meanings inboth the study of anatomy and the field of orthopaedics. Use of suchanatomical reference terms in the written description and claims isintended to be consistent with their well-understood meanings unlessnoted otherwise. Additionally, the term “about” may be used in thespecification in reference to certain measurements that are definedwithin manufacturing tolerances. That is, the provided measurementsand/or numerical values may deviate, in practice, due to tolerancesinherent in the machine or fabrication process.

References in the specification to “one embodiment,” “an embodiment,”“an illustrative embodiment,” etc., indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but every embodiment may or may not necessarily includethat particular feature, structure, or characteristic. Moreover, suchphrases are not necessarily referring to the same embodiment. Further,when a particular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the art to effect such feature, structure,or characteristic in connection with other embodiments whether or notexplicitly described. Additionally, it should be appreciated that itemsincluded in a list in the form of “at least one A, B, and C” can mean(A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C).Similarly, items listed in the form of “at least one of A, B, or C” canmean (A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C).

In the drawings, some structural or method features may be shown inspecific arrangements and/or orderings. However, it should beappreciated that such specific arrangements and/or orderings may not berequired. Rather, in some embodiments, such features may be arranged ina different manner and/or order than shown in the illustrative figures.Additionally, the inclusion of a structural or method feature in aparticular figure is not meant to imply that such feature is required inall embodiments and, in some embodiments, may not be included or may becombined with other features.

Referring now to FIGS. 1-3 , in an illustrative embodiment, anorthopaedic knee prosthesis 100 includes a femoral component 102 and atibial insert 104. Additionally, the orthopaedic knee prosthesis 100 mayinclude a tibial tray (not shown) to which the tibial insert 104 iscoupled during use. The femoral component 102 (and the tibial tray) areillustratively formed from a metallic material such as cobalt-chromiumor titanium, but may be formed from other materials, such as a ceramicmaterial, a polymer material, a bio-engineered material, or the like, inother embodiments. The tibial insert 104 is illustratively formed from apolymer material such as an ultra-high molecular weight polyethylene(UHMWPE), but may be formed from other materials, such as a ceramicmaterial, a metallic material, a bio-engineered material, or the like,in other embodiments.

The femoral component 102 is configured to be coupled to asurgically-prepared surface of the distal end of a patient's femur (notshown), and the tibial insert 104 is configured to be coupled to asurgically-prepared surface of the proximal end of a patient's tibia(not shown) via, for example, a tibial tray (not shown). Alternatively,in other embodiments, the tibial insert 104 may be configured to attachto the surgically-prepared surface of the proximal end of the patient'stibia directly, without use of a tibial tray. For example, the tibialinsert 104 and a polymer “tray” may be combined into a single polymericcomponent.

In use, the femoral component 102 is configured to articulate with thetibial insert 104. To do so, the femoral component includes an outer,articulating surface 110 having a lateral condyle 112 and a medialcondyle 114. Similarly, the tibial insert 104 includes an articularsurface 120 having lateral articular surface 122 and a medial articularsurface 124. As such, the lateral condyle 112 is configured toarticulate with the lateral articular surface 122, and the medialcondyle 114 is configured to articulate with a medial articular surface124 of the tibial insert as shown in FIGS. 28-31 .

As discussed in more detail below, each of the femoral component 102 andthe tibial insert 104 include articular curvatures and related featuresthat facilitate or promote pivoting of the lateral condyle 112 on thelateral articular surface 122, while limiting or reducing anteriortranslation of the medial condyle 114 on the medial articular surface124 during flexion. For example, one or both of the condyles 112, 114include a sagittal condylar surface having a curved surface sectiondefined by a continuously decreasing radius of curvature. Additionally,the medial articular surface 124 has a concave sagittal curvature thatis overall more conforming with a convex sagittal curvature of themedial condyle 114 at a degree of mid-flexion (e.g., 30 degrees) than atextension. The lateral and medial articular surfaces 122, 124 of thetibial insert 104 are also asymmetrically shaped to provide asymmetricpivoting of the femoral component 102 on the tibial insert 104.Additionally, the lateral articular surface 122 and the lateral condyle112 may be less conforming with each other than the medial articularsurface 124 and the medial condyle 114. Furthermore, as discussed below,the coronal curvature of the lateral articular surface 122 is uniform inthe anterior-posterior direction, while the coronal curvature of themedial articular surface 124 is non-uniform in the anterior-posteriordirection (e.g., the coronal curvature of the medial articular surface124 is defined by multiple, different coronal curvatures). Additionally,the medial articular surface 124 may be more conforming with the medialcondyle 114 in extension, compared to flexion and more conforminganterior of a dwell point of the medial condyle 114 (see discussion ofFIGS. 18-27 below) than at the dwell point, due to the sagittal shape ofthe medial articular surface 124. It should be appreciated that thesagittal curvature of the femoral condyles 112, 114, the overallsagittal conformity between the medial condyle 114 and the medialarticular surface 124, the asymmetry of the lateral and medial articularsurfaces 122, 124, the increased conformity in extension and anterior ofthe dwell point of the medial condyle 114 improves the stability of theorthopaedic knee prosthesis 100, facilitates pivoting of the lateralfemoral condyle 112, and reduces or restricts medial anteriortranslation of the femur.

As discussed above, the femoral component 102 is configured to becoupled to a surgically-prepared surface of the distal end of apatient's femur (not shown) and may be secured to the patient's femurvia use of bone adhesive or other attachment means. The femoralcomponent 102 includes the lateral condyle 112 and the medial condyle114, which are spaced apart to define an intercondylar opening 116therebetween. In use, the condyles 112, 114 replace the natural condylesof the patient's femur and are configured to articulate on thecorresponding lateral and medial articular surfaces 122, 124 of thetibial insert 104 as discussed above.

Referring now to FIG. 4 , one or both of the condyles 112, 114 of thefemoral component 102 include a condyle surface 400, which is convexlycurved in the sagittal plane. Illustratively, the condyle surface 400 isformed from a number of curved surface sections 402, 404, 406, 408, 410,and 412 each of which is tangent to the adjacent curved surface section.Each curved surface sections 402, 404, 406, 408, 410, and 412 contactsthe tibial bearing insert through different ranges of degrees offlexion. For example, the curved surface sections 402, 404 of thecondyle surface 400 contact the tibial insert 104 during early flexion.The curved surface sections 406, 408 of the condyle surface 400 contactthe tibial insert 104 during mid-flexion. And, the curved surfacesections 410, 412 of the condyle surface 400 contact the tibial insert104 during late flexion.

Each curved surface sections 402, 406, 408, 410, and 412 is defined by aconstant radius of curvature R1, R3, R4, R5, and R6, respectively.However, as discussed in more detail below, the curved surface section404 is defined by a plurality of rays, rather than a constant radius ofcurvature. In particular, the curved surface section 3604 is designed totransition gradually the condyle surface 400 from the radius ofcurvature R1 of the curved surface section 402 to a radius of curvatureR2, which is tangent to the curved surface section 406. As such, thecurved surface section 3604 has a continuously decreasing radius ofcurvature.

In the illustrative embodiment as shown in table 500 of FIG. 5 , thecurved surface section 402 defined by the radius of curvature R1 rangesfrom a first degree of flexion of −5 degrees to a second degree offlexion of 5 degrees. The curved section 404 defined by the radius ofcurvature R2 ranges from a first degree of flexion of 5 degrees to asecond degree of flexion of 65 degrees. The curved section 406 definedby the radius of curvature R3 ranges from a first degree of flexion of65 degrees to a second degree of flexion of 90 degrees. The curvedsection 408 defined by the radius of curvature R4 ranges from a firstdegree of flexion of 90 degrees to a second degree of flexion of 105degrees. The curved section 410 defined by the radius of curvature R5ranges from a first degree of flexion of 105 degrees to a second degreeof flexion of 120 degrees. And, the curved section 412 defined by theradius of curvature R6 ranges from a first degree of flexion of 120degrees to a second degree of flexion of 163 degrees (or 155 degreesdepending on the size). In other embodiments, any of the curved surfacesections 402, 406, 408, 410, and 412 have range across a differentnumber of degrees.

As shown in FIG. 6 , a table 600 defines the length of each radius ofcurvature R1, R2, R3, R4, R5, and R6, for a family of femoral componentsizes 1 through 10. As illustrated in the table 600, while theparticular length of each radius of curvature R1, R2, R3, R4, R5, R6 foreach size 1-10 of the femoral component 102 may vary across sizes, theratios of R1/R2, R1/R3, and R1/R4 are relatively constant, or varyslightly, across the femoral component sizes. For example, the ratio ofthe radius of curvature R1 to the radius of curvature R2 may vary in arange of about 1.347 to 1.355, to maintain a value of about 1.350 acrossthe femoral component sizes 1 through 10. Similarly, the ratio of theradius of curvature R1 to the radius of curvature R3 may vary in a rangeof about 1.277 to 1.278, to maintain a value of about 1.280 across thefemoral component sizes 1 through 10. Furthermore, the ratio of theradius of curvature R1 to the radius of curvature R4 may be maintainedat a value of about 1.305 across the femoral component sizes 1 through10.

It should also be appreciated that the condyle surface 400 of thefemoral component 102 is designed such that the radius of curvature R3is greater than the radius of curvature R2 by an amount in the range ofabout 0.5 millimeters to about 5 millimeters in some embodiments. Asdiscussed below, the particular amount of increase may be based on thesize of the femoral component in some embodiments. Additionally, basedon the above analysis, the condyle surface 400 is designed such that theincrease in the radius of curvature from R2 to R3 occurs at a degree offlexion in the range of about 45 degrees to about 90 degrees. In oneparticular embodiment, the increase in radius of curvature from R2 to R3occurs at about 65 degrees of flexion on the condyle surface 400.

As discussed above, the curved surface section 404 is designed toprovide a gradual transition from the radius of curvature R1 to theradius of curvature R2. As such, the size of the angle defined by thecurved surface section 404 may be selected based on the desired rate oftransition. For example, in some embodiments, the condyle surface 400 ofthe femoral component 102 is designed such that the curved surfacesection 404 extends from a first degree of flexion in the range of about0.0 to about 30.0 degrees to a second degree of flexion in the range ofabout 45.0 to about 90.0 degrees of flexion. In one particularembodiment, the curved surface section 404 extends from about 5.0degrees of flexion to about 65.0 degrees of flexion, as discussed above.

It should be appreciated that the particular amount of increase in theradius of curvature R2 to R3 of the condyle surface 400 of the femoralcomponent 102 and/or the positioning of such increase on the condylesurface 400 may also be based on, scaled, or otherwise affected by thesize of the femoral component 102. That is, it should be appreciatedthat an increase of the radius of curvature R2 to R3 of the condylesurface 400 of 0.5 millimeters is a relatively larger increase insmall-sized femoral components compared to larger-sized femoralcomponents. As such, the magnitude of the increase in the radius ofcurvature R2 to R3 of the condyle surface 400 of the femoral component102 may change across femoral component sizes. In some embodiments,however, the ratios of the radius of curvatures R1 to the radius ofcurvatures R2, R3, and R4 are maintained at a substantially constantvalue across the family of femoral component sizes.

As discussed above, the curved surface section 404 is designed toprovide a gradual transition from the radius of curvature R1 to theradius of curvature R2. To do so, the curved surface section 404 isdefined by a plurality of rays 420, which originate from a common originO. Each of the plurality of rays 420 defines a respective contact pointon the curved surface section 404. The location of each of those contactpoints, which collectively define the curved surface section 404, can bedetermined based on the length of each ray 420 at each degree of flexionaccording to the following polynomial equation:r _(θ)=(a+(b*θ)+(c*θ ²)+(d*θ ³)),  (3)

wherein “r_(θ)” is the length of a ray 420 (in metric units) defining acontact point on the curved surface section 404 at “θ” degrees offlexion, “a” is a scalar value between 20 and 50, and “b” is acoefficient value selected such that:−0.30<b<0.00,0.00<b<0.30, orb=0  (4)

If the selected coefficient “b” is in the range of −0.30<b<0.00, thencoefficients “c” and “d” are selected such that:0.00<c<0.012, and−0.00015<d<0.00.  (5)

Alternatively, if the selected coefficient “b” is in the range of0.00<b<0.30, then coefficients “c” and “d” are selected such that:−0.010<c<0.00, and−0.00015<d<0.00.  (6)

Further, if the selected coefficient “b” is equal to 0, thencoefficients “c” and “d” are selected such that:−0.0020<c<0.00, or0.00<c<0.0025, and−0.00015<d<0.00.  (7)

It should be appreciated that ranges of values for the scalar “a” andcoefficients “b”, “c”, and “d” are a subset of an infinite number ofpossible solutions for the polynomial equation (3). That is, theparticular set of ranges provided above have been determined from aninfinite number of possibilities to generate a family of curves (i.e.,the curved surface section 404) that provide a gradual transitioning ofthe condyle surface 400 from the radius of curvature R1 to the radius ofcurvature R2 such that anterior translation of the femoral component 102relative to the tibial insert 104 (e.g., anterior translation of themedial side) is reduced or delayed. Additionally, it should beappreciated that the range of values for each coefficient “a”, ‘b”, “c”,and “d” are provided above in regard to embodiments designed using themetric system of units. However, such range of coefficient values may beconverted for use in embodiments using other systems of units such asthe English system of units.

The overall shape of the curved surface section 404 is also affected bythe placement of the common origin O of the plurality of rays 420. Bylimiting the distance between the common origin O of the plurality ofrays 420 and the origin 422 of the radius of curvature R1, which definesthe early flexion curved surface section 402, paradoxical anteriorsliding of the femoral component 102 on the tibial insert 104 may bereduced or delayed. As such, in one embodiment, the location of thecommon origin O of the plurality of rays 420 is selected such that thedistance between the common origin O and the origin 422 of the radius ofcurvature R1 is less than about 10 millimeters. It should be appreciatedthat the distance between the common origin O and the origin 422 of theradius of curvature R1 and the particular coefficient values may bedependent upon the particular size of the femoral component 102 in someembodiments. An illustrative embodiment of distances between the commonorigin O and the origin 422 of the radius of curvature R1 and theparticular coefficient values for equation (3) are shown in table 700 ofFIG. 7 .

In other embodiments, the curved surface section 404 may be designed toprovide a gradual transition from the radius of curvature R1 to theradius of curvature R2 using other geometry. For example, the radiiforming the curved surface section 404 may not have common origin butmay be of the same length. In such embodiment, the origin of each radiiis moved along a spiral to provide a gradual transition from the radiusof curvature R1 to the radius of curvature R2. Additionally, in yetother embodiments, the curved surface section 404 may be formed from aplurality of small curved sections each having a small arc length (e.g.,1 degree) and each defined by a constant radius that decreases relativeto the anterior-most adjacent small curved section.

Referring now to FIGS. 8-18 , the illustrative tibial insert 104includes a body 800, which includes the asymmetrical lateral and medialarticular surfaces 122, 124. The medial articular surface 124 includes adwell point 802, which defines a distal most point of the medialarticular surface 124 and, generally, the contact point or region atwhich the medial condyle 114 of the femoral component 102 contacts themedial articular surface 124 during articulation (although some contactbetween the femoral component 102 and the tibial insert 104 may occuranterior to the medial dwell point 802 at some degrees flexion anddepending on loading of the femoral component 102 and tibial insert 104.

Illustratively, the dwell point 802 is located on the medial articularsurface 124 in relation to an anterior sidewall 810 of the body 800 ofthe tibial insert 104. For example, in the illustrative embodiment, thedwell point 802 is located on the medial articular surface 124 adistance 820 that is about 63.3% of the overall medialanterior-posterior length 822, which is defined as the distance from ananterior-most point on the anterior sidewall 810 to a posterior-mostpoint on a posterior sidewall 812 of the body 800 of the tibial insert104 on the medial side (i.e., measured across the medial articularsurface 124). It should be appreciated that in some embodiments, thelateral articular surface 122 and the medial articular surface 124 mayhave different anterior-posterior lengths due to differentposterior-most points on the posterior sidewall 812.

Unlike the dwell point 802 of the medial articular surface 124, thelateral articular surface 122 includes a dwell region 804 (shown as asolid line in FIG. 8 ), which defines a distal-most region of thelateral articular surface 122. The dwell region 804 is embodied as aregion of contact because the dwell region 804 corresponds to asemi-planar or semi-flat section of the “sagittal” curvature of thelateral articular surface 122. As used herein, the term “semi-planar”refers to a section that is either planar or is otherwise defined by aradius that is at least three times the length of the radius ofcurvature of the adjacent curved section as discussed in more detailbelow. That is, the dwell region 804 may be embodied as a surfacesection that is defined by a large enough radius of curvature that thecurvature of the dwell region 804 approximates a planar section whenviewed in a cross-section taken along the arcuate articular path 806.

The dwell region 804 lies on an arcuate articular path 806 of thelateral articular surface 122, which defines a path of contact pointsbetween the lateral condyle 112 of the femoral component 102 and thelateral articular surface 122 through flexion of the femoral component102 (although the lateral condyle 112 may not travel the completearcuate articular path 806 during normal flexion). The arcuate path 806is defined by a radius of curvature 808, which has an origin congruentwith the dwell point 802 of the medial articular surface 124 or within areference distance thereof. In the illustrative embodiment, the lengthof the radius of curvature 808 is design to match, within manufacturingtolerances, the pitch of the condyles 112, 114 of the femoral component102 (i.e., the distance between the distal-most points on each condyle112, 114). As such, the curvature of the lateral articular surface 122is designed to allow the femoral component 102 to pivot or rotate,relative to the dwell point 802, along the arcuate articular path 806during flexion of the femoral component 102. That is, as the femoralcomponent 102 is moved from extension through flexion, the contact pointbetween the lateral condyle 112 of the femoral component 102 and thelateral articular surface 122 moves posteriorly along the arcuate path806.

Similar to the dwell point 802, the dwell point 804 is illustrativelylocated on the lateral articular surface 122 in relation to the anteriorsidewall 810 of the body 800 of the tibial insert 104. For example, inthe illustrative embodiment, the dwell point 804 is located on thelateral articular surface 122 a distance 920 that is about 62.6% of theoverall lateral anterior-posterior length 922, which is defined as thedistance from an anterior-most point on the anterior sidewall 810 to aposterior-most point on a posterior sidewall 812 of the body 800 of thetibial insert 104 on the lateral side (i.e., measured across the lateralarticular surface 122). Again, it should be appreciated that in someembodiments, the lateral articular surface 122 and the medial articularsurface 124 may have different anterior-posterior lengths due todifferent posterior-most points on the posterior sidewall 812.

Additionally, as shown in FIG. 9 , the dwell point 802 of the medialarticular surface 124 is spatially related to the dwell region 804 ofthe lateral articular surface 122. Specifically, the dwell region 804has a length 900 defined as the distance between an anterior-most end902 of the dwell region 804 (shown as a solid point on FIG. 9 ) and aposterior-most end 904 of the dwell region 804 (also shown as a solidpoint on FIG. 9 ), and the dwell point 802 is located on the medialarticular surface 124 between the anterior-most end 902 and theposterior-most end 904 of the dwell region 804. That is the dwell point804 is located on the medial articular surface 124 between an anterior,imaginary medial-lateral bisecting line 910 that includes theanterior-most end 902 of the dwell region 804 and a posterior, imaginarymedial-lateral bisecting line 912 that includes the posterior-most end904 of the dwell region 804. Additionally, as shown in FIG. 9 , thedwell point 804 is located on the medial articular surface 124 posteriorto a midpoint 906 of the dwell region 804 (shown as a solid point onFIG. 9 ). That is the dwell point 804 is located on the medial articularsurface 124 posterior to an imaginary medial-lateral bisecting line 914that includes the midpoint 906 of the dwell region 804.

As shown in FIGS. 10 and 11 , the body 800 of the tibial insert 104includes a bottom side 1000, which is configured to confront a platformof a tibial tray (not shown) during implantation as discussed above. Theillustrative tibial insert 104 includes a posterior channel 1002 sizedand shaped to receive a posterior buttress of the tibial tray. Theposterior channel 1002 is defined by sidewalls 1004, which includesflanges 1006 that extend inwardly into the posterior channel 1002 andare positioned to be received in undercuts of the corresponding tibialtray. The tibial insert 104 also includes an anterior channel 1010 thatis sized and shaped to receive an anterior buttress of the correspondingtibial tray. In this way, the channels 1002, 1010 cooperate withfeatures of the corresponding tibial tray to lock the tibial insert 104onto the tibial tray in a single orientation relative to the tibialtray. It should be appreciated that in other embodiments the tibialinsert 104 and a corresponding tibial tray may include mobile bearinginterface that allows the tibial insert 104 to move independent of thecorresponding tibial tray. Additionally, as discussed above, the tibialinsert 104 may be configured to attach directly to the patient's tibiain some embodiments. In such embodiments, the tibial insert 104 may notinclude the features described above for coupling to a tibial tray andmay include other geometry that allows for implantation of the tibialinsert 104 directly onto the patient's bony anatomy.

As discussed above, the medial articular surface 124 and the lateralarticular surface 122 are asymmetric to each other. For example, as bestshown in FIGS. 12-17 , the medial articular surface 124 has an anteriorlip that is higher than an anterior lip of the lateral articular surface122. For example, as shown in FIG. 16 , the lateral articular surface122 includes a lateral anterior lip 1600, which defines the lip or rimof the anterior sidewall 810 on the lateral side. The lateral anteriorlip 1600 has a lip height 1602 defined by a vertical distance (i.e., aninferior-superior distance) between the lateral dwell point/region 804of the tibial insert 104 and the lateral anterior lip 1600. Similarly,as shown in FIG. 17 , the medial articular surface 124 includes a medialanterior lip 1700, which defines the lip or rim of the anterior sidewall810 on the medial side. The medial anterior lip 1700 has a lip height1702 defined by a vertical distance (i.e., an inferior-superiordistance) between the medial dwell point 802 of the tibial insert 104and the medial anterior lip 1700. In the illustrative embodiment, thelip height 1702 of the medial anterior lip 1700 is greater than the lipheight 1602 of the lateral anterior lip 1600.

Additionally, the dwell point 802 of the medial articular surface 124 ispositioned such that a ratio between the distance 1710 of the medialdwell point 802 and the anterior sidewall 810 to the lip height 1702 isrelatively constant across sizes of the tibial insert 104. For example,in one illustrative embodiment, the ratio between the lip height 1702 tothe dwell point distance 1710 is in the range of 18.9% to 20.9%,depending on the size of the tibial insert 104.

Referring now to FIGS. 18-27 , as discussed above the lateral and medialarticular surfaces 122, 124 have different contours such that thearticular surfaces 122, 124 are asymmetric with each other. For example,as shown in FIG. 18 , the lateral articular surface 122 includes aconcave curvature 1802 when viewed in an anterior-posterior complexcross-section taken along the arcuate articular path 806. It should beappreciated that the anterior-posterior complex concave curvature 1802of the arcuate articular path 806 does not lie on a single sagittalplane due to the arcuate shape of the arcuate articular path 806 whenviewed in a transverse plane. Additionally, the lateral articularsurface 122 has a concave curvature 1812 when viewed in a cross-sectiontaken orthogonal to the arcuate articular path 806. The cross-sectionalconcave curvature 1812 is uniform at each point along the arcuatearticular path 806 (shown in FIG. 18 by multiple concave curvatures1812). That is, the cross-section concave curvature 1812 of the arcuatearticular path 806 is uniform along the arcuate articular path 806 inthe general anterior-to-posterior direction (which also curves in themedial-lateral direction due to the arcuate shape of the arcuatearticular path 806). Again, it should be appreciated that thecross-section concave curvature 1812 does not lie directly on thecoronal planes of the lateral articular surface 122 due to the arcuateshape of the arcuate articular path 806 when viewed in a transverseplane.

Conversely, the medial articular surface 124 is defined by a sagittalconcave curvature 1804 and a plurality of non-uniform coronal curvatures1814, 1824, 1834. However, as indicated in FIG. 18 , the coronalcurvature of the medial articular surface 124 is uniform posteriorly ofthe medial dwell point 802 and defined by the coronal curvature 1814.Conversely, anterior of the medial dwell point 802, the coronalcurvature of the medial articular surface is non-uniform and defined bythe coronal curvatures 1824 and 1834.

In some embodiments, the coronal conformity between the medial articularsurface 124 and the medial condyle 114 in not uniform across the coronalcurvatures 1814, 1824, 1834 and/or across degrees of flexion of thefemoral component 102 on the tibial insert 104. For example, in theillustrative embodiment, the coronal conformity between the medialarticular surface 124 and the medial condyle 114 (i.e., the amount atwhich the radius of curvature defining the coronal curvature of themedial articular surface 124 at a particular contact point and theradius of curvature defining the contact point (or region) of thecondyle surface 400 of the medial condyle 114 match) is less between thecoronal curvature 1814 and the condyle surface 400 of the medial condyle114 at a particular degree of flexion (e.g., at 30.0 degrees of flexion)than between the coronal curvature 1824 or 1834 and the condyle surface400 of the medial condyle 114 at the particular degree of flexion. Thatis, at a particular degree of flexion, the coronal conformity betweenthe coronal curvature 1824 and the condyle surface 400 of the medialcondyle 114 is greater than the coronal conformity between the coronalcurvature 1814 (e.g., at the medial dwell point 802) and the condylesurface 400 of the medial condyle 114. While the coronal curvature ofthe medial articular surface 124 is design so as to avoid impingementand/or unintended contact between the femoral component 102 and thetibial insert 104, it should also be appreciated that because thecoronal conformity between the medial articular surface 124 and themedial condyle 114 increases anterior of the medial dwell point 802 at aparticular degree of flexion (e.g., at 30.0 degrees of flexion),anterior translation of the medial condyle 114 may be limited,restricted, or otherwise reduced.

Referring now to FIG. 20 , an illustrative embodiment of theanterior-posterior complex concave curvature 1802 of the lateralarticular surface 122 is shown in a cross-section of the tibial insert104 taken generally along the line 20-20 of FIG. 19 (i.e., along thearcuate articular path 806). The illustrative anterior-posterior complexconcave curvature 1802 includes a semi-planar section 2000 correspondingto the dwell region 804, a first set of curved sections extendingposteriorly of the flat section 2000 and an anterior curved section 2006extending anteriorly of the flat section 2000. The first set of curvedsections illustratively include a first curved section 2002 and a secondcurved section 2004.

As discussed above the flat section 2000 (i.e., the dwell region 804) issemi-planar and extends from anterior-most end 902 to a posterior-mostend 904. Again, the flat section 2000 is “semi-planar” in that it may bedefined as a planar section as shown in FIG. 20 or as a curved sectionhaving a radius that is sufficiently large so as to approximate a planarsection. For example, in an illustrative embodiment, the flat section2000 is defined by a large radius of curvature 2010 that has a length ofat least three times the length of a radius of curvature that defineseither adjacent curved section (i.e., curved section 2012 and curvedsection 2016). In such embodiments, the flat section 2000 includes adwell point 2090 that defines the distal-most point of the flat section2000 and extends for about 1.15 degrees anterior of the dwell point 2090and about 1.58 degrees posterior of the dwell point 2090 for a total arclength of about 2.73 degrees.

Illustratively, the first curved section 2002 of the first set of curvedsections extends posteriorly from the posterior-most end 904 of the flatsection 2000 for about 3.4 degrees and is defined by a constant radiusof curvature 2012. The second curved section 2004 is adjacent to thefirst curved section 2002, extends posteriorly therefrom for an arclength in the range of about 13.2 degrees to about 13.7 degreesdepending on the size of the tibial insert 104. The second curvedsection 2004 is defined by a constant radius of curvature 2014. In anillustrative embodiment, the radius of curvature 2014 is less than theradius of curvature 2012 (i.e., the radii of curvature of theanterior-posterior complex concave curvature 1802 decrease posteriorly).In other embodiments, however, the first set of curved sections thatextend posteriorly from the flat section 2000 may include additionalcurved sections to smoothly open up the posterior side of theanterior-posterior complex concave curvature 1802 and/or be defined by agradually or continuously decreasing radii as discussed above in regardto the femoral component 102.

The anterior curved section 2006 extends anteriorly from theanterior-most end 902 of the flat section 2000 for an arc length in therange of about 33.5 degrees to about 34.4 degrees, depending on the sizeof the tibial insert 104. In an illustrative embodiment, the radius ofcurvature 2016 is less than the radius of curvature 2012 and greaterthan the radius of curvature 2014.

Referring now to FIG. 21 , in another embodiment, the anterior-posteriorcomplex concave curvature 1802 may include a flat or planer section 2100corresponding to the dwell region 804, a first set of curved sectionsextending posteriorly of the flat section 2100 and a second set ofcurved sections extending anteriorly of the flat section 2100. Asdiscussed above the flat section 2100 (i.e., the dwell region 804)extends from anterior-most end 902 to a posterior-most end 904.

The first set of curved sections illustratively include a first curvedsection 2102, a second curved section 2104, a third curved section 2106,and a fourth curved section 2108. The first curved section 2102 extendsfor about 5.0 degrees and is defined by a constant radius of curvature2122. The second curved section 2104 extends for about 5.0 degrees andis defined by a constant radius of curvature 2124. The third curvedsection 2106 extends for about 5.0 degrees and is defined by a constantradius of curvature 2126. And, the fourth curved section 2108 extendsfor 18.0 degrees and is defined by a constant radius of curvature 2128.In some embodiments, however, the first set of curved sections thatextend posteriorly from the flat section 2100 may include additionalcurved sections to smoothly open up the posterior side of theanterior-posterior complex concave curvature 1802 and/or be defined by agradually or continuously decreasing radii as discussed above in regardto the femoral component 102. In an illustrative embodiment, the radiiof curvature of the first sec of curved sections increases posteriorly.That is, the radius of curvature 2128 is greater than the radius ofcurvature 2126, which is greater than the radius of curvature 2124,which is greater than the radius of curvature 2122.

The second set of curved sections illustratively includes a fifth curvedsection 2110 and a sixth curved section 2112. The fifth curved section2110 extends for about 15.0 degrees and is defined by a radius ofcurvature 2130. And, the sixth curved section 2112 extends for about35.0 degrees and is defined by a radius of curvature 2132. In anillustrative embodiment, the radius of curvature 2130 is greater thanthe radius of curvature 2132.

Referring now to FIG. 22 , an illustrative embodiment of the medialsagittal concave curvature 1804 of the tibial insert 104 is shown in across-section taken generally along the line 22-22 of FIG. 19 , whichgenerally matches the sagittal concave curvature 1804 of FIG. 18 . Theillustrative medial sagittal concave curvature 1804 includes a firstcurved section 2200, a second curved section 2202 anteriorly adjacentthe first curved section 2200, third curved section 2204 anteriorlyadjacent the second curved section 2202, a fourth curved section 2206anteriorly adjacent the third curved section, and a fifth curved section2208 posteriorly adjacent the first curved section 2200. Illustratively,the medial dwell point 802 lies at the intersection of the first curvedsection 2200 and the fifth curved section 2208. However, in otherembodiments, the dwell point 802 may lie on the first curved section2200 or the fifth curved section 2208.

The first curved section 2200 extends from the dwell point 802anteriorly for about 5.2 degrees and is defined by a constant radius ofcurvature 2210. The second curved section 2202 extends anteriorly fromthe first curved section 2200 for an arc length in the range of about14.8 degrees to about 24.8 degrees, depending on the size of the tibialinsert 104, and is defined by a constant radius of curvature 2212. Thethird curved section 2204 extends anteriorly from the second curvedsection 2202 for an arc length in the range of about 10.7 degrees toabout 20.7 degrees, depending on the size of the tibial insert 104, andis defined by a constant radius of curvature 2214. The fourth curvedsection 2206 extends anteriorly from the third curved section 2204 foran arc length in the range of about 0.2 degrees to about 6.3 degrees,depending on the size of the tibial insert 104, and is defined by aconstant radius of curvature 2216. And, the fifth curved section 2208extends posteriorly from the first curved section 2200 for an arc lengthin the range of about 15.9 degrees to about 17.4 degrees, depending onthe size of the tibial insert 104, and is defined by a constant radiusof curvature 2218. In an illustrative embodiment, the radius ofcurvature 2218 is greater than the radius of curvature 2210.Additionally, in an illustrative embodiment, the radius of curvature2212 is less than each of the radii of curvatures 2210, 2214, and 2216.

The medial sagittal concave curvature 1804 of the tibial insert 104 maybe shaped differently to have a different curvature in otherembodiments. For example, in another embodiment, the second curvedsection 2202 may extend anteriorly from the first curved section 2200for about 24.8 degrees. The third curved section 2204 may extendanteriorly from the second curved section 2202 for about 15.0 degrees.And, the fifth curved section 2208 may extend posteriorly from the firstcurved section 2200 for about 19.0 degrees.

In some embodiments, the sagittal conformity between the medialarticular surface 124 and the medial condyle 114 is not uniform acrossdegrees of flexion. For example, as discussed in more detail below inregard to FIGS. 28-43 , the overall sagittal conformity between themedial sagittal concave curvature 1804 of the tibial insert 104 and thesagittal convex curvature of the medial condyle 114 of the femoralcomponent 102 may be greater at a particular degree of flexion (e.g., at30 degrees of flexion) than at extension. The overall sagittalconformity between the sagittal curvatures of the femoral component 102and the tibial insert 104 (i.e., the conformity across the completesagittal curvature rather than only at a particular contact point) canbe defined as the amount of overall gap between those curvatures at aparticular degree of flexion. As such, the sagittal curvature of themedial condyle 114 of the femoral component 102 matches the sagittalcurvature of the medial articular surface 124 of the tibial insert thegreatest amount at the particular degree of flexion (e.g., at 30 degreesof flexion). The sagittal conformity may be increased further underloading conditions (i.e., the femoral component 102 may be compressedfurther onto the tibial insert 104 such that the sagittal conformity atthe particular degree of flexion is further increased). By increasingthe overall sagittal conformity between the medial condyle 114 and themedial articular surface 124 during flexion, relative to extension,anterior translation of the femoral component 102 on the medialarticular surface 124 may be reduced at that particular degree offlexion (e.g., at 30 or 35 degrees of flexion).

Additionally, at a particular degree of flexion (e.g., 30 degrees offlexion) the sagittal conformity between the medial condyle 114 and thesagittal curvatures 2200, 2202, 2204, 2206. For example, in anillustrative embodiment, the sagittal conformity between the medialarticular surface 124 and the medial condyle 114 (i.e., the amount atwhich the radius of curvature defining the sagittal curvature of themedial articular surface 124 at a particular contact point and theradius of curvature defining the contact point on the condyle surface400 of the medial condyle 114 match) is less between the fourth curvedsection 2206 and the condyle surface 400 of the medial condyle 114 at aparticular degree of flexion (e.g., at 30.0 degrees of flexion) thanbetween the first curved section 2200 and the condyle surface 400 of themedial condyle 114 at the particular degree of flexion. That is, at aparticular degree of flexion, the sagittal conformity at the point (orregion) of contact between the first curved section 2200 and the condylesurface 400 of the medial condyle 114 is greater than the sagittalconformity between the point (or region) of contact between the fourthcurved section 2206 and the condyle surface 400 of the medial condyle114. As such, it should be appreciated that because the sagittalconformity between the medial articular surface 124 and the medialcondyle 114 increases anterior of the medial dwell point 802 at aparticular degree of flexion (e.g., at 30.0 degrees of flexion),anterior translation of the medial condyle 114 on the medial articularsurface 124 may be limited, restricted, or otherwise reduced.

Additionally, it should be appreciated that the sagittal conformitybetween the medial articular surface 124 and the medial condyle 114 atthe medial dwell point 802 may increase through a particular range offlexion in some embodiments. For example, in an illustrative embodiment,as the femoral component 102 is flexed through a particular range offlexion, the point of contact between the femoral component 102 and thetibial insert 104 moves along the curved surface section 404 defined bythe decreasing radii of curvature. As such, in the illustrativeembodiment, the sagittal curvature of the medial articular surface 124at the medial dwell point 802 is designed to have the greatest amount ofsagittal conformity with the medial condyle 114 at a particular degreeof flexion (e.g., at 30 degrees of flexion) at which the point ofcontact between the femoral component 102 and the tibial insert 104occurs on the curved surface section 404, resulting in an increasingamount of sagittal conformity between the femoral component 102 and thetibial insert 104 as the particular degree of flexion is approached.

Referring now to FIG. 23 , an illustrative embodiment of thecross-section concave curvature 1812 of the lateral articular surface122 of the tibial insert 104 is shown in a cross-section taken generallyalong the line 23-23 of FIG. 19 , which generally matches the uniformcross-section curvature 1812 of FIG. 18 . As discussed above, in theillustrative embodiment, the cross-section curvature 1812 of the lateralarticular surface 122 is uniform along the anterior-posterior complexconcave curvature 1802 and has a single curved section 2300 having aconstant radius of curvature 2302. The curved section 2300 extendsmedially (i.e., inboard) of the lateral dwell region 804 for about 25degrees and extends laterally (i.e., outboard) of the lateral dwellregion 804 for an arc length in the range of about 18.7 degrees to about31.1 degrees for an overall arc length of about 43.7 degrees to about56.1 degrees, depending on the size of the tibial insert 104.Additionally, the cross-section curvature 1812 of the lateral articularsurface 122 includes a planar section 2310 that is tangent to andextends medially of (i.e., inboard) the medial-most point of the curvedsection 2300. Additionally, as shown in FIG. 23 , the planar section2310 is angled relative to the bottom side 1000 of the tibial insert 104at an angle 2320 of about 25.0 degrees. The size, shape, and orientationof the planar section 2310 may be selected or designed to match theinboard shape of the femoral component 102 and/or to avoid impingementof the femoral component 102.

Referring now to FIG. 24 , an illustrative embodiment of the coronalcurvature 1814 of the tibial insert 104 is shown in a cross-sectiontaken generally along the line 24-24 of FIG. 19 , which generallymatches the coronal curvature 1814 of FIG. 18 . In the illustrativeembodiment, the coronal curvature 1814 of the medial articular surface124 is uniform posterior of the medial dwell point 802 and has a singlecurved section 2400 having a constant radius of curvature 2402.

The curved section 2400 extends laterally (i.e., inboard) of the medialdwell point 802 for about 25 degrees and extends medially (i.e.,outboard) of the medial dwell point 802 for an arc length in the rangeof about 18.6 degrees to about 26.8 degrees for an overall arc length ofabout 43.6 degrees to about 51.8 degrees, depending on the size of thetibial insert 104. Additionally, the coronal curvature 1814 of themedial articular surface 124 includes a planar section 2410 that istangent to and extends laterally of (i.e., inboard) the lateral-mostpoint of the curved section 2400. As shown in FIG. 24 , the planarsection 2410 is angled relative to the bottom side 1000 of the tibialinsert 104 at an angle 2420 of about 25.0 degrees. Similarly, to planarsection 2310 of the lateral articular surface 122, the size, shape, andorientation of the planar section 2410 may be selected or designed tomatch the inboard shape of the femoral component 102 and/or to avoidimpingement of the femoral component 102.

In other embodiments, the coronal curvature 1814 may be defined by aplurality of curved sections. For example, as shown in FIG. 25 , inanother embodiment, the coronal curvature 1814 may be defined by a firstcurved section 2500 on which the dwell point 802 lies and a secondcurved section 2502 located medially adjacent (i.e., outboard of) thefirst curved section 2500. The first curved section 2500 extends forabout 20 degrees and is defined by a radius of curvature 2510, and thesecond curved section 2502 extends for about 10 degrees and is definedby a radius of curvature 2512. In such embodiments, the radius ofcurvature 2512 may be greater than the radius of curvature 2510.Additionally, the coronal curvature 1814 of FIG. 25 may include a planarsection 2504 that is tangent to and extends laterally of (i.e., inboard)the lateral-most point of the curved section 2500. Similar to planarsection 2410, the planar section 2504 may be angled relative to thebottom side 1000 of the tibial insert 104 at an angle of about 25.0degrees.

Referring now to FIG. 26 , an illustrative embodiment of the coronalcurvature 1824 of the tibial insert 104 is shown in a cross-sectiontaken generally along the line 26-26 of FIG. 19 , which generallymatches the coronal curvature 1824 of FIG. 18 . The coronal curvature1824 crosses the sagittal concave curvature 1804 at an anterior-mostpoint of the second curved section 2202 that defines the medial sagittalconcave curvature 1804 (see FIG. 22 ). The coronal curvature 1824includes a flat or planar section 2600 having a lateral end 2602 (i.e.,an inboard end) and a medial end 2604 (i.e., an outboard end), a firstcurved section 2606 extending from the medial end 2604 of the planarsection 2600, and a second curved section 2608 extending from thelateral end 2602 of the planar section 2600. The first curved section2606 extends for an arc length in the range of about 14.7 degrees toabout 15.7 degrees, depending on the size of the tibial insert 104, andis defined by a constant radius of curvature 2616. The second curvedsection 2608 extends for an arc length in the range of about 20.1degrees to about 28.5 degrees, depending on the size of the tibialinsert 104, and is defined by a constant radius of curvature 2618. Inthe illustrative embodiment, the radius of curvature 2618 is greaterthan the radius of curvature 2616.

Referring now to FIG. 27 , an illustrative embodiment of the coronalcurvature 1834 of the tibial insert 104 is shown in a cross-sectiontaken generally along the line 27-27 of FIG. 19 , which generallymatches the coronal curvature 1834 of FIG. 18 . The coronal curvature1834 crosses the sagittal concave curvature 1804 at an anterior-mostpoint of the third curved section 2204 that defines the medial sagittalconcave curvature 1804 (see FIG. 22 ). Similar to the coronal curvature1824, the coronal curvature 1834 includes a flat or planar section 2700having a lateral end 2702 (i.e., an inboard end) and a medial end 2704(i.e., an outboard end), a first curved section 2706 extending from themedial end 2704 of the planar section 2700, and a second curved section2708 extending from the lateral end 2702 of the planar section 2700. Insome embodiments, the planar section 2700 may be angled relative to thebottom side 1000 of the tibial insert 104 at about 6.0 degrees. Thefirst curved section 2706 extends for an arc length in the range ofabout 0.3 degrees to about 0.9 degrees, depending on the size of thetibial insert 104, and is defined by a constant radius of curvature2616. The second curved section 2708 extends for an arc length in therange of about 16.4 degrees to about 24.7 degrees, depending on the sizeof the tibial insert 104, and is defined by a constant radius ofcurvature 2718. In the illustrative embodiment, the radius of curvature2716 is greater than the radius of curvature 2718.

Referring now to FIGS. 28-43 , as discussed above, the femoral component102 is configured to articulate on the tibial insert 104 through a rangeof degrees of flexion. For example, the femoral component 102 is shownat extension (i.e., 0 degrees of flexion) in FIG. 28 . In FIG. 29 , thefemoral component 102 has articulated to about 35 degrees of flexion. InFIG. 30 , the femoral component 102 has articulated to about 90 degreesof flexion. And, in FIG. 31 , the femoral component 102 has articulatedto about 110 degrees of flexion.

As discussed above, the condyles 112, 114 of the femoral component 102may have a different amount of conformity with the articular surfaces122, 124 at different degrees of flexion. For example, in FIGS. 32-34 ,the orthopaedic prosthesis 100 is shown at about 0.0 degrees of flexion.As indicated in FIG. 32 , the femoral component 102 and the tibialinsert 104 have an increase coronal conformity when in extension.Additionally, as shown in FIG. 33 , the femoral component 102 is onlyslightly pivoted or rotated on the tibial insert 104. Furthermore, asshown in FIG. 34 , the medial condyle 114 and the medial articularsurface 124 have an overall sagittal conformity (i.e., the amount ofspace between the sagittal curvatures of the medial condyle 114 and themedial articular surface 124) at extension.

In FIGS. 35-37 , the orthopaedic prosthesis 100 is shown at 35.0 degreesof flexion. As indicated in FIG. 35 , the femoral component 102 and thetibial insert 104 has a slightly less coronal conformity relative to theextension position. Additionally, as shown in FIG. 36 , the femoralcomponent 102 is pivoted or rotated on the tibial insert 104 to agreater amount. Furthermore, as shown in FIG. 37 , the medial condyle114 and the medial articular surface 124 have an overall sagittalconformity that is increased relative to the 0.0 degrees of flexion ofFIG. 34 .

In FIGS. 38-40 , the orthopaedic prosthesis 100 is shown at about 90degrees of flexion. As indicated in FIG. 38 , the femoral component 102and the tibial insert 104 has less coronal conformity relative to the 35degrees of flexion of FIGS. 34 and 35 . Additionally, as shown in FIG.39 , the femoral component 102 is pivoted or rotated on the tibialinsert 104 to a greater amount relative to 35 degrees of flexion ofFIGS. 35 and 36 . Furthermore, as shown in FIG. 40 , the medial condyle114 and the medial articular surface 124 have an overall sagittalconformity that is decreased relative to the 35.0 degrees of flexion ofFIG. 37 .

In FIGS. 41-43 , the orthopaedic prosthesis 100 is shown at about 110degrees of flexion. As indicated in FIG. 41 , the femoral component 102and the tibial insert 104 has less coronal conformity relative to the 90degrees of flexion of FIGS. 38 and 39 . Additionally, as shown in FIG.42 , the femoral component 102 is pivoted or rotated on the tibialinsert 104 to a greater amount relative to 90 degrees of flexion ofFIGS. 38 and 39 . Furthermore, as shown in FIG. 43 , the medial condyle114 and the medial articular surface 124 have an overall sagittalconformity that is further decreased relative to the 90.0 degrees offlexion of FIG. 40 .

Referring now to FIGS. 44 and 45 , as the femoral component 102 is movedthrough a range of flexion, the condyle surface 400 of the medialcondyle 114 contacts the medial dwell point 802 of the tibial insert 104at different points on contact on the condyle surface 400. For example,an illustrative embodiment, as the femoral component 102 moves fromabout 65 degrees of flexion to a degree of flexion greater than 65degrees, the point of contact between the femoral component 102 and thetibial insert 104 moves from the curved surface section 404 defined bythe decreasing radii of curvature to the curved surface section 406defined by a radius of curvature that is greater than the posterior-mostradii of curvature of the curved surface section 404. In doing so, thedistance between the origin that defines the radius of curvature of thepoint of contact between the femoral component 102 and the tibial insertincreases.

For example, FIG. 44 illustrates the femoral component 102 at a firstdegree of flexion at which a point of contact 4400 between the condylesurface 400 of the medial condyle 114 of the femoral component 102 andthe tibial insert 104 is located at the dwell point 802 of the tibialinsert 104 and is defined by a posterior-most radii 4402 of theplurality of decreasing radii that define the curved surface section404. The posterior-most radii 4402 has an origin 4404 that is located adistance 4410 from the medial dwell point 802.

In FIG. 45 , the femoral component 102 has been moved to a second degreeof flexion, slightly greater than the first degree of flexion, at whicha point of contact 4500 between the condyle surface 400 of the medialcondyle 114 of the femoral component 102 and the tibial insert 104 islocated at the dwell point 802 of the tibial insert 104 and is definedby a constant radius of curvature 4502 that defines the curved surfacesection 406 (i.e., radius of curvature R3 of FIG. 4 ). The constantradius of curvature 4502 has an origin 4504 that is located a distance4510 from the medial dwell point 802. It should be appreciated that thedistance 4510 between the origin 4504 and the medial dwell point 802 isgreater than the distance 4410 between the origin 4404 and the medialdwell point 802. As such, the increase in distance between the origins4404, 4504 as the point of contact between the femoral component 102 andthe tibial insert 104 moves from the curved surface section 404 to thecurved section 406 of the condyle surface 400 of the medial condyle 114extends the tibial-femoral envelope, which increases tension on theligaments of the knee joint and may improve stability of the knee joint.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as illustrative and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the methods, apparatuses, and/or systemsdescribed herein. It will be noted that alternative embodiments of themethods, apparatuses, and systems of the present disclosure may notinclude all of the features described yet still benefit from at leastsome of the advantages of such features. Those of ordinary skill in theart may readily devise their own implementations of the methods,apparatuses, and systems that incorporate one or more of the features ofthe present invention and fall within the spirit and scope of thepresent disclosure as defined by the appended claims.

The invention claimed is:
 1. An orthopaedic knee prosthesis comprising:a femoral component having a lateral condyle and a medial condyle,wherein the medial condyle includes a femoral articular surface definedby a plurality of curved femoral surface sections that includes a firstcurved femoral surface section defined by a continually decreasingradius of curvature; and a tibial insert having a lateral articularsurface configured to articulate with the lateral condyle of the femoralcomponent and a medial articular surface configured to articulate withthe medial condyle of the femoral component, wherein the medialarticular surface is asymmetrically shaped relative to the lateralarticular surface and includes a medial dwell point that defines adistal-most point on the medial articular surface, wherein the medialcondyle contacts the medial dwell point at a first contact point on thefirst curved femoral surface section at a first degree of flexion andcontacts the medial dwell point at a second contact point on the firstcurved femoral surface section at a second degree of flexion, whereinthe second contact point is posterior of the first contact point andwherein the second degree of flexion is greater than the first degree offlexion, and wherein the medial articular surface includes a sagittalconcave curvature that has a first sagittal conformity with the medialcondyle at a location anterior to dwell point at the first degree offlexion and a second sagittal conformity with the medial condyle at thelocation anterior to the dwell point at the second degree of flexion,wherein the second sagittal conformity is greater than the firstsagittal conformity to reduce anterior translation of the medial condyleat the second degree of flexion.
 2. The orthopaedic knee prosthesis ofclaim 1, wherein the medial condyle of femoral component includes asagittal convex curvature, and wherein a sagittal conformity between thesagittal concave curvature of the medial articular surface and sagittalconcave curvature of the medial condyle is greater at a first degree offlexion of the femoral condyle than at extension.
 3. The orthopaedicknee prosthesis of claim 1, wherein the medial articular surfaceincludes a coronal concave curvature and wherein a coronal conformitybetween the coronal concave curvature and the medial condyle at thedegree of flexion is greater at the medial dwell point of the medialarticular surface than at the location on the medial articular surfacethat is anterior of the medial dwell point, and wherein the medialarticular surface is non-uniform anterior of the medial dwell point anduniform posterior of the medial dwell point.
 4. The orthopaedic kneeprosthesis of claim 1, wherein the medial condyle and the medialarticular surface are more conforming with each other than the lateralcondyle and the lateral articular surface.
 5. The orthopaedic kneeprosthesis of claim 1, wherein the medial articular surface includes acoronal concave curvature and wherein a coronal conformity between thecoronal concave curvature and the medial condyle is greater when thefemoral component is positioned at extension than when the femoralcomponent is positioned at a later degree of flexion.
 6. The orthopaedicknee prosthesis of claim 1, wherein the lateral articular surfaceincludes an arcuate articular path that when viewed in a cross-sectionplane has a curvature that includes a planar section, an anterior curvedsection located anterior of the semi-planar section, and a plurality ofposterior curved sections located posterior of the planar section, andwherein the semi-planar section defines a distal-most area of thelateral articular surface and wherein each posterior curved section isdefined by a corresponding radius of curvature, and wherein the radii ofcurvature of the plurality of posterior curved sections decreaseposteriorly.
 7. The orthopaedic knee prosthesis of claim 1, wherein thesagittal concave curvature of the medial articular surface, when viewedin a sagittal plane, includes a plurality of curved sections and whereinthe medial dwell point is located on the sagittal concave curvature, andwherein the plurality of curved sections includes a first curved sectionadjacent to the medial dwell point and extending posterior therefrom, asecond curved section adjacent the medial dwell point and extendinganterior therefrom, a third curved section adjacent to the second curvedsection and extending anterior therefrom, a fourth curved sectionadjacent to the third curved section and extending anterior therefrom,and a fifth curved section adjacent the fourth curved section andextending anterior therefrom, wherein a radius of curvature of the firstcurved section is greater than a radius of curvature of the secondcurved section and wherein a radius of curvature of the third curvedsection is less that the radius of curvature of the second curvedsection, less than a radius of curvature of the fourth curved section,and less than a radius of the fifth radius of curvature.
 8. Theorthopaedic knee prosthesis of claim 1, wherein a distal-most point ofthe femoral articular surface when the femoral component is in extensiondefines zero degrees of flexion, and wherein the first curved femoralsurface section extends from a first degree of flexion of about 5degrees to a second degree of flexion of about 65 degrees and is definedby a plurality of rays extending from a common origin to a correspondingpoint on the second curved femoral surface section, and wherein each rayhas a length defined by the following polynomial equation:r _(θ)=(a+(b*θ)+(c*θ ²)+(d*θ ³)), wherein r_(θ) is the length of the raydefining a point on the second curved femoral surface section at θdegrees of flexion, a is a coefficient value between 20 and 50, and b isa coefficient value in a range selected from the group consisting of:−0.30<b<0.00, 0.00<b<0.30, and b=0, wherein when b is in the range of−0.30<b<0.00, (i) c is a coefficient value between 0.00 and 0.012 and(ii) d is a coefficient value between −0.00015 and 0.00, wherein when bis in the range of 0<b<0.30, (i) c is a coefficient value between −0.010and 0.00 and (ii) d is a coefficient value between −0.00015 and 0.00,and wherein when b is equal to 0, (i) c is a coefficient value in arange selected from the group consisting of: −0.0020<c<0.00 and0.00<c<0.0025 and (ii) d is a coefficient value between −0.00015 and0.00.
 9. The orthopaedic knee prosthesis of claim 8, wherein theplurality of curved femoral surface sections includes a second curvedfemoral surface section posteriorly adjacent the first curved femoralsection, wherein the second curved femoral surface section is defined bya constant radius of curvature greater than a posterior-most radii ofcurvature of the first curved femoral surface section.
 10. Anorthopaedic knee prosthesis comprising: a femoral component having alateral condyle and a medial condyle, wherein the medial condyleincludes a femoral articular surface defined by a plurality of curvedfemoral surface sections that includes a first curved femoral surfacesection and a second curved femoral surface section posteriorly adjacentthe first curved femoral surface section, wherein the first curvedfemoral surface section is defined by a continually decreasing radius ofcurvature and the second curved femoral surface section is defined by aconstant radius of curvature greater than a posterior-most radii ofcurvature of the first curved femoral surface section; and a tibialinsert having a lateral articular surface configured to articulate withthe lateral condyle of the femoral component and a medial articularsurface configured to articulate with the medial condyle of the femoralcomponent, wherein the medial articular surface is asymmetrically shapedrelative to the lateral articular surface and includes a medial dwellpoint that defines a distal-most point on the medial articular surface,wherein the medial condyle (i) contacts the medial dwell point at afirst contact point on the first curved femoral surface section at afirst degree of flexion, the first contact point being defined by theposterior-most radii of curvature of the first curved femoral surfacesection and (ii) contacts the medial dwell point at a second contactpoint on the second curved femoral surface section at a second degree offlexion greater than the first degree of flexion, the second contactpoint being defined by the constant radius of curvature of the secondcurved femoral surface section, and wherein an inferior-superiordistance between the medial dwell point and an origin of the constantradius of curvature of the second curved femoral surface section at thesecond degree of flexion is greater than an inferior-superior distancebetween the medial dwell point and an origin of the posterior-most radiiof curvature of the first curved femoral surface section at the firstdegree of flexion.
 11. The orthopaedic knee prosthesis of claim 10,wherein the medial condyle of femoral component includes a sagittalconvex curvature and the medial articular surface includes a sagittalconcave curvature, and wherein a sagittal conformity between thesagittal concave curvature of the medial articular surface and sagittalconcave curvature of the medial condyle is greater at a first degree offlexion of the femoral condyle than at extension.
 12. The orthopaedicknee prosthesis of claim 10, wherein the medial articular surfaceincludes a sagittal concave curvature, wherein at the medial dwell pointthe sagittal concave curvature has a first sagittal conformity with themedial condyle at a first degree of flexion of the femoral component,wherein at a location on the medial articular surface that is anteriorof the medial dwell point the sagittal concave curvature has a secondsagittal conformity with the medial condyle at the first degree offlexion, and wherein the second sagittal conformity is greater than thefirst sagittal conformity.
 13. The orthopaedic knee prosthesis of claim10, wherein a distal-most point of the femoral articular surface whenthe femoral component is in extension defines zero degrees of flexion,and wherein the first curved femoral surface section extends from afirst degree of flexion of about 5 degrees to a second degree of flexionof about 65 degrees and is defined by a plurality of rays extending froma common origin to a corresponding point on the second curved femoralsurface section, and wherein each ray has a length defined by thefollowing polynomial equation:r _(θ)=(a+(b*θ)+(c*θ ²)+(d*θ ³)), wherein r_(θ) is the length of the raydefining a point on the second curved femoral surface section at θdegrees of flexion, a is a coefficient value between 20 and 50, and b isa coefficient value in a range selected from the group consisting of:−0.30<b<0.00, 0.00<b<0.30, and b=0, wherein when b is in the range of−0.30<b<0.00, (i) c is a coefficient value between 0.00 and 0.012 and(ii) d is a coefficient value between −0.00015 and 0.00, wherein when bis in the range of 0<b<0.30, (i) c is a coefficient value between −0.010and 0.00 and (ii) d is a coefficient value between −0.00015 and 0.00,and wherein when b is equal to 0, (i) c is a coefficient value in arange selected from the group consisting of: −0.0020<c<0.00 and0.00<c<0.0025 and (ii) d is a coefficient value between −0.00015 and0.00.
 14. The orthopaedic knee prosthesis of claim 13, wherein theplurality of curved femoral surface sections includes a second curvedfemoral surface section posteriorly adjacent the first curved femoralsection, wherein the second curved femoral surface section is defined bya constant radius of curvature greater than a posterior-most radii ofcurvature of the first curved femoral surface section.
 15. Anorthopaedic knee prosthesis comprising: a femoral component having alateral condyle and a medial condyle, wherein the medial condyleincludes a femoral articular surface defined by a plurality of curvedfemoral surface sections that includes a first curved femoral surfacesection defined by a continually decreasing radius of curvature; and atibial insert having a lateral articular surface configured toarticulate with the lateral condyle of the femoral component and amedial articular surface configured to articulate with the medialcondyle of the femoral component, wherein the lateral articular surfaceincludes an arcuate articular path extending in an anterior-posteriordirection, wherein the arcuate articular path when viewed in across-section plane has a curvature that includes a planar section andwherein the planar section defines a distal-most area of the lateralarticular surface, and wherein the medial articular surface isasymmetrically shaped relative to the lateral articular surface andincludes a medial dwell point that defines a distal-most point of themedial condyle surface, and wherein the medial dwell point is located onthe medial condyle surface (i) between a first imaginary medial-lateralbisecting line of the tibial insert that includes an anterior-most endof the planar section of the sagittal curvature of the lateral articularsurface and a second imaginary medial-lateral bisecting line of thetibial insert that includes a posterior-most end of the planar sectionof the sagittal curvature of the lateral articular surface and (ii)posterior to an anterior-posterior midpoint of the planar section of thesagittal curvature of the lateral articular surface.
 16. The orthopaedicknee prosthesis of claim 15, wherein the medial condyle of femoralcomponent includes a sagittal convex curvature and the medial articularsurface includes a sagittal concave curvature, and wherein a sagittalconformity between the sagittal concave curvature of the medialarticular surface and sagittal concave curvature of the medial condyleis greater at a first degree of flexion of the femoral condyle than atextension.
 17. The orthopaedic knee prosthesis of claim 15, wherein themedial articular surface includes a sagittal concave curvature, whereinat the medial dwell point the sagittal concave curvature has a firstsagittal conformity with the medial condyle at a first degree of flexionof the femoral component, wherein at a location on the medial articularsurface that is anterior of the medial dwell point the sagittal concavecurvature has a second sagittal conformity with the medial condyle atthe first degree of flexion, and wherein the second sagittal conformityis greater than the first sagittal conformity.
 18. The orthopaedic kneeprosthesis of claim 17, wherein the medial articular surface includes acoronal concave curvature, wherein at the medial dwell point the coronalconcave curvature has a first coronal conformity with the medial condyleat the first degree of flexion, wherein at the location on the medialarticular surface that is anterior of the medial dwell point the coronalconcave curvature has a second coronal conformity with the medialcondyle at the first degree of flexion, and wherein the second coronalconformity is greater than the first coronal conformity.
 19. Theorthopaedic knee prosthesis of claim 15, wherein a distal-most point ofthe femoral articular surface when the femoral component is in extensiondefines zero degrees of flexion, and wherein the first curved femoralsurface section extends from a first degree of flexion of about 5degrees to a second degree of flexion of about 65 degrees and is definedby a plurality of rays extending from a common origin to a correspondingpoint on the second curved femoral surface section, and wherein each rayhas a length defined by the following polynomial equation:r _(θ)=(a+(b*θ)+(c*θ ²)+(d*θ ³)), wherein r_(θ) is the length of the raydefining a point on the second curved femoral surface section at θdegrees of flexion, a is a coefficient value between 20 and 50, and b isa coefficient value in a range selected from the group consisting of:−0.30<b<0.00, 0.00<b<0.30, and b=0, wherein when b is in the range of−0.30<b<0.00, (i) c is a coefficient value between 0.00 and 0.012 and(ii) d is a coefficient value between −0.00015 and 0.00, wherein when bis in the range of 0<b<0.30, (i) c is a coefficient value between −0.010and 0.00 and (ii) d is a coefficient value between −0.00015 and 0.00,and wherein when b is equal to 0, (i) c is a coefficient value in arange selected from the group consisting of: −0.0020<c<0.00 and0.00<c<0.0025 and (ii) d is a coefficient value between −0.00015 and0.00.
 20. The orthopaedic knee prosthesis of claim 19, wherein theplurality of curved femoral surface sections includes a second curvedfemoral surface section posteriorly adjacent the first curved femoralsection, wherein the second curved femoral surface section is defined bya constant radius of curvature greater than a posterior-most radii ofcurvature of the first curved femoral surface section.